. 


MERCHANT 
VESSELS 


BY 

ROBERT  RIEGEL,  Ph.D. 

PROFESSOR    OF  INSURANCE  AND  STATISTICS 
IN  THE  UNIVERSITY   OF  PENNSYLVANIA 


D.  APPLETON  AND  COMPANY 

NEW  YORK  LONDON 

1921 


' 


COPYRIGHT,   1921,  BY 

D.  APPLETON  AND  COMPANY 


PRINTED   IN    THE    UNITED    STATES    OT   AMERICA 


EDITORS'  PREFACE 

THIS  is  the  fourth  volume  of  a  series  dealing  with  the  business 
of  ocean  shipping  and  transportation.  The  first  volume,  Ocean 
Steamship  Traffic  Management,  by  Professor  G.  G.  Huebner,  bore 
the  following  Editors'  Preface : 

"This  volume  upon  the  management  of  ocean  steamship  traffic 
is  the  first  of  a  series  of  manuals  designed  to  assist  young  men 
in  training  for  the  shipping  business.  The  necessity  for  such 
a  series  of  manuals  became  evident  when,  as  a  result  of  the  great 
war,  the  tonnage  of  vessels  under  the  American  Flag  was,  within 
a  brief  period,  increased  many  fold.  To  carry  on  the  war,  and 
to  meet  the  demands  of  ocean  commerce  after  the  war,  the  United 
States  Government,  through  the  Shipping  Board  and  private  ship- 
yards, brought  into  existence  a  large  mercantile  marine.  If  these 
ships  are  to  continue  in  profitable  operation  under  the  American 
Flag,  the  people  of  the  United  States  must  be  trained  to  operate 
them.  Steamship  companies,  ship-brokers  and  freight  forwarders 
must  all  be  able  to  secure  men  necessary  to  carry  on  the  commer- 
cial and  shipping  activities  that  make  use  of  the  ships.  A  suc- 
cessful merchant  marine  requires  ships,  men  to  man  the  ships, 
and  business  organization  to  give  employment  to  the  vessels. 

"In  its  Bulletin  upon  'Vocational  Education  for  Foreign  Trade 
and  Shipping'  (since  republished  as  'Training  for  Foreign  Trade/ 
Miscellaneous  Series  No.  97,  Bureau  of  Foreign  and  Domestic 
Commerce,  for  sale  by  the  Superintendent  of  Documents),  the 
Federal  Board  for  Vocational  Education  includes  among  other 
courses  suggested  for  foreign  trade  training  two  shipping  courses 
upon  subjects  with  which  exporters  should  be  familiar,  namely, 
'Principles  of  Ocean  Transportation'  and  'Ports  and  Terminals/ 
Although  such  general  courses  are  helpful  to  the  person  engaging 
in  the  exporting  business,  a  training  for  the  steamship  business 
as  a  profession  requires  much  greater  detail  in  the  knowledge  of 

v 

£52574 


vi  EDITORS'  PREFACE 

concrete  facts  of  a  routine  nature.  An  analysis  was  made  of  the 
various  divisions  of  the  steamship  office  organization  and  it  was 
suggested  to  the  United  States  Shipping  Board  that  as  no  litera- 
ture existed  of  sufficient  practicability  and  detail,  several  manuals 
covering  the  principal  features  of  shore  operations  should  be 
written. 

"The  response  of  the  Shipping  Board  was  hearty.  The  Ship- 
ping Board  appointed  Mr.  Emory  R.  Johnson  of  its  staff,  then 
conducting  an  investigation  of  ocean  rates  and  terminal  charges, 
as  editor.  The  Federal  Board  for  Vocational  Education  desig- 
nated Mr.  R.  S.  MacElwee,  then  engaged  in  the  preparation  of 
studies  in  foreign  commerce.  Before  the  project  was  completed 
Mr.  Johnson  severed  his  connection  with  the  Shipping  Board,  in 
1919,  and  in  January,  1919,  Mr.  MacElwee  became  Assistant 
Director  of  the  Bureau  of  Foreign  and  Domestic  Commerce, 
Department  of  Commerce.  The  interest  of  the  editors  in  the 
project  did  not  terminate,  however,  and  their  close  cooperation 
has  been  voluntarily  continued  out  of  conviction  that  the  works 
will  be  helpful. 

"The  books  have  been  written  with  a  view  to  their  being  read 
by  individual  students  conducting  their  studies  without  guidance, 
also  with  the  expectation  that  they  will  be  used  as  class  text- 
books. Doubtless  colleges,  technical  institutes,  and  high  schools 
having  courses  in  foreign  trade,  shipping  business  and  ocean 
transportation  will  desire  to  use  these  volumes  as  class  texts  in  a 
manner  outlined  in  'Training  for  the  Steamship  Business,'  by  R. 
S.  MacElwee,  Miscellaneous  Series  98,  Bureau  of  Foreign  and 
Domestic  Commerce,  Superintendent  of  Documents,  Washington, 
D.  C.  It  is  expected  that  evening  classes  and  part-time  schools 
organized  under  the  patronage  of  the  Federal  Board  for  Voca- 
tional Education,  Chambers  of  Commerce,  and  other  interested 
organizations  will  find  the  manuals  useful.  Should  these  volumes 
accomplish  the  desired  purpose  of  giving  the  American  people  a 
somewhat  greater  proficiency  in  the  business  of  operating  ships, 
they  will  have  proven  successful." 

This  volume  upon  Merchant  Vessels  contains  a  non-techni- 
cal, amply  illustrated  description  of  the  main  types  of  vessels  and 
their  uses  in  different  services.  The  discussion  of  the  many  prob- 
lems connected  with  the  measurement  of  vessels,  their  registra- 


EDITOR'S  PREFACE  vii 

tion,  and  tlieir  tonnage  is  especially  clear  and  valuable.  The  book 
should  be  of  interest  to  all  students  of  ocean  transportation,  to 
shippers,  to  vessel-owners,  and  to  those  engaged  in  the  operation 
of  vessels. 

THE  EDITORS 


AUTHOR'S  PREFACE 

THIS  is  one  of  a  "Shipping  Series"  designed  as  a  basis  for  in- 
struction in  the  various  phases  of  the  steamship  business,  a  se- 
ries inspired  and  outlined  by  the  editors,  Dr.  Emory  R.  Johnson 
and  Dr.  R.  S.  MacElwee.  As  a  part  of  such  a  series  it  assumes 
the  form  of  a  specialized  text,  supplementing  and  being  sup- 
plemented by  the  other  volumes  of  the  series;  but  an  effort  has 
been  made  to  describe  a  definite  phase  of  the  steamship  business 
and  in  this  particular  field  to  produce  a  volume  complete  in 
itself.  It  deals  with  the  vessels  of  various  types  and  equip- 
ment employed  in  maritime  commerce,  their  measurement  and 
classification. 

Part  I  describes  the  competition  between  sail  and  steam;  the 
uses  of  the  sailing  vessel ;  wood,  steel  and  concrete  ships  and 
their  more  essential  parts;  the  various  types  of  vessels  employed 
and  their  uses;  and  the  principal  kinds  of  marine  engines.  In 
this  Part  the  types  of  vessels  and  their  purposes  have  been 
given  exceptional  space.  The  treatment  is  intended  to  be  eco- 
nomic in  character  and  no  pretense  is  made  of  writing  a  tech- 
nical treatise;  on  the  contrary  the  sections  dealing  with  con- 
struction features  and  marine  engines  have  been  made  as  clear 
and  brief  as  possible  and  the  advantages  and  disadvantages  of 
the  various  features  emphasized.  The  diagrams  are  intended 
to  give  accurate  general  impressions  rather  than  mechanical 
details  and  photographs  have  been  employed  in  some  cases. 
Much  of  the  information  contained  has  hitherto  existed  only 
in  such  scattered  form  as  to  be  inaccessible  to  the  average  stu- 
dent of  transportation. 

Part  II  deals  with  a  phase  of  shipping  activity  upon  which 
the  available  literature  is  noticeably  scant.  Aside  from  brief 
general  remarks,  government  documents  and  foreign  works,  com- 
paratively little  information  has  been  available  on  the  pur- 
poses of  vessel  measurement,  the  units  and  methods  employed, 
vessel  measurement  rules  and  the  work  of  classification  socie- 

ix 


x  AUTHOR'S  PREFACE 

ties,  in  spite  of  the  political,  legal  and  economic  significance  of 
these  subjects.  American  rules,  practices  and  institutions  have 
been  emphasized,  since  foreign  examples  have  often  been  pre- 
sented elsewhere. 

In  preparing  the  list  of  references  which  appears  at  the  end 
of  nearly  every  chapter  the  endeavor  has  been  to  include  those 
which  are  accessible  and  which  contain  a  reasonable  amount 
of  additional  material  on  the  subject  in  a  form  suitable  for  the 
average  reader,  avoiding  the  usual  complete  but  cumbersome 
"bibliography,"  which  fortunately  is  elsewhere  available.  Un- 
fortunately but  inevitably  this  often  excluded  excellent  and  val- 
uable books,  sometimes  those  from  which  the  author  derived 
considerable  assistance  but  whose  technical  character  or  inac- 
cessibility made  them  unavailable  for  the  purpose. 

It  is  a  pleasure  to  acknowledge  the  benefit  derived  from  the 
advice  and  assistance  of  Dr.  Emory  R.  Johnson  and  the  in- 
formation furnished  by  the  Bureau  of  Navigation,  the  Col- 
lector of  Customs  at  Philadelphia,  officials  of  the  Shipping 
Board,  Mr.  G.  P.  Taylor  of  the  American  Bureau  of  Shipping 
and  vessel  owners. 

ROBERT  RIEGEL 


CONTENTS 

PART  I 

CONSTRUCTION,  TYPES  AND  USES  OF  MERCHANT 
VESSELS 

CHAPTER  PAGE 

I.    METHODS  OF  PROPULSION 3 

Types  of  sailing  vessels — The  square  and  fore-and-aft 
rig — Combinations  of  these  rigs — The  schooner  the  im- 
portant modern  sailing  vessel — Decline  in  importance  of 
the  sailing  vessel — Causes  of  this  decline — The  favor- 
able features  of  sailing  vessels — Their  uses  at  the  pres- 
ent time — Summary — References. 

II.     MATERIALS  OF  CONSTRUCTION 18 

Essential  construction  features  of  a  wooden  vessel — 
Disadvantages  of  wood  as  a  material  for  shipbuilding — 
Introduction  of  iron  vessels — Advantages  of  steel  over 
iron — The  composite  vessel — Concrete  vessels — Their 
advantages  and  defects — Statistics  of  wood,  iron  and 
steel  construction — References. 

III.  STRUCTURAL  FEATURES  OF  STEEL  VESSELS 32 

Longitudinal  and  transverse  members — Principal  trans- 
verse parts  and  their  uses — Longitudinal  parts  and  their 
uses — The  Isherwood  system  of  construction — Double 
bottom  tanks — Forms,  spaces  and  superstructures — Ref- 
erences. 

IV.  TYPES  OF  MERCHANT  VESSELS 48 

A  classification  of  vessels — Classification  of  merchant 
vessels  according  to  hull  material — Classification  ac- 
cording to  form  of  hull — Classification  according  to 
speed  and  character  of  service — Comparison  of  line  and 
tramp  vessels  as  regards  standardization,  types  of  cargo, 
contracts,  methods  of  operation,  types  of  vessels  em- 
ployed, relative  economy,  rates,  earnings  and  extent  of 
r-  tonnage. 

V.     TYPES  OF  MERCHANT  VESSELS  (Continued) 66 

Classification  according  to  strength  of  construction  and 
deck  arrangements— Relation  of  the  load  line  to  type — 
xi 


xii  CONTENTS 

CHAPTER  PAGE 

Full-scantling  vessel — Three-deck  vessel — Two-deck 
vessel — One-deck  vessel — Raised-quarterdeck  vessel — 
Shelter-deck  vessel — Well-deck  vessel — Flush-deck  ves- 
sel with  superstructures — Shade-deck  vessel — Whale- 
back  steamer — Turret-deck  vessel — Trunk-deck  vessel — 
Self-trimming  vessel — Cantilever  vessel — Corrugated 
vessel — Tank  vessel — Refrigerator  vessel — Steam 
schooner — Awning-deck  vessel — Spar-deck  vessel — Un- 
rigged craft — Modern  developments  in  cargo  vessels — 
References. 

VI.    TYPES  OF  MARINE  ENGINES 103 

Classification  of  steam  engines — The  beam  engine — 
Side-lever  engine — Oscillating  engine — Compound  en- 
gine— Trunk  engine — Modern  reciprocating  engines — 
Turbine  engines — Types  of  turbine  engines — Advan- 
tages and  disadvantages  of  the  turbine — Marine  boilers 
— References. 

VII.  OIL-BURNING  AND  INTERNAL-COMBUSTION  ENGINES  .  .119 
Oil-burning  engines — Their  advantages  and  disadvan- 
tages as  compared  with  coal-burning  engines — Internal- 
combustion  gas  engines — Method  of  operation — Advan- 
tages and  disadvantages  of  the  producer-gas  engine — 
Internal-combustion  oil  engines — Operation  of  the 
Diesel  engine — Advantages  of  the  Diesel  engine — Ref- 
erences. 

PART  II 
THE  MEASUREMENT  OF  MERCHANT  VESSELS 

VIII.    KINDS  OF  TONNAGE  AND  THEIR  USES 137 

Various  meanings  of  the  word  ton — Relations  between 
different  forms  of  tonnage — Uses  of  vessel  tonnage — 
Uses  of  displacement  and  dead-weight  tonnage — Use  for 
statistical  purposes — Legal  use — Taxation — Charges  for 
services  rendered — Description  of  vessels — Uses  of 
gross  and  net  tonnage — Statistical  purposes — Legal 
purposes — As  a  basis  for  taxation — As  a  basis  for  serv- 
ices rendered — Description  of  vessels. 

IX.  DISPLACEMENT  AND  DEAD- WEIGHT  TONNAGE  .  .  .  .157 
Displacement  tonnage — Displacement  and  buoyancy — 
Forms  of  displacement — Calculation  of  displacement — 
Displacement  curve — Immersion  curve — Dead-weight 
tonnage — Measurement  of  dead-weight — Dead-weight 
scale — Relation  between  displacement  and  dead-weight 
— Rules  for  freeboard — Load  line  legislation — Princi- 


CONTENTS  xiii 

CHAPTER  PAGE 

pies  of  load  line  legislation — United  States'  legisla- 
tion— References. 

X.    GROSS  TONNAGE 176 

Definition  of  gross  tonnage — Steps  in  the  process  of 
measurement — Measurement  process  under  United 
States  rules — Tonnage  under  the  tonnage  deck — 'Tween- 
decks  tonnage — Superstructures  and  closed-in  spaces — 
Spaces  exempt  because  unenclosed — Spaces  exempt  be- 
cause of  their  purpose — Principles  governing  gross  ton- 
nage measurement. 

XI.    NET  TONNAGE 192 

Nature  of  net  tonnage — Measurement  of  propelling- 
power  space — Deductions  for  propelling  space — Deduc- 
tions for  crew  space — Deductions  for  navigating  space 
— Principles  of  net  tjonnage— Example  of  calculation  of 
United  States  tonnage — References. 

XII.    COMPARISON  OF  MEASUREMENT  RULES 203 

Important  present-day  measurement  rules — Summary  of 
the  measurement  process — Comparison  of  United  States, 
British,  German,  Suez  Canal  and  Panama  Canal  rules — 
Tonnage  under  the  tonnage  deck — Between-deck  ton- 
nage— Superstructures — Spaces  exempt  below  the  ton- 
nage deck — Spaces  exempt  above  the  tonnage  deck — 
Measurement  of  propeller-power  space — Necessity  for 
arbitrary  rule — The  percentage  method — The  Danube 
rule — The  German  rule — Discussion  of  deductions  for 
propelling  power — Deductions  for  crew  space — Deduc- 
tions for  navigating  space — International  tonnage — 
References. 

XIII.    THE  MEASUREMENT  OF  SAFETY 229 

Purposes  of  vessel  classification — Development  of 
classification  societies — Process  of  registration — De- 
scription of  Lloyds'  Register — Other  important  registers 
— American  Bureau  of  Shipping — Description  of  the 
American  Register — Lloyd's  rules  and  tables  for  classi- 
fication— American  Bureau  of  Shipping  rules  for  con- 
struction— References. 


LIST  OF  ILLUSTRATIONS 

FIGURE  PAGE 

Frontispiece — Whaleback  steamer 

1.  Full-rigged  ship 4 

2.  Schooner .      .  5 

3.  Net  tonnage  of  world's  merchant^  marine 6 

4.  Sail  and  steam  tonnage  of  the  United  States     .....  7 

5.  Sailing  vessel  routes  of  the  world 10 

6.  Principal  parts  of  a  wooden  vessel 20 

7.  Vessel  stresses  in  still  water    .     .      .      . 22 

8.  Vessel  stresses  in  waves 23 

9.  Transverse  stress            24 

10.  World's  merchant  marine — wood,  iron  and  steel    ....  30 

11.  Keels 33 

12.  Transverse  frames 34 

13.  Frame  and  shell  plating      .                             35 

14.  Frames  and  floor  plate 35 

15.  Keelson  and  stringers * 36 

16.  Beams  and  carlings 37 

17.  Floor  plates  and  double  bottom 38 

18.  Longitudinal  system  of  framing — exterior        .....  39 

19.  Transverse  system  of  framing 40 

20.  Longitudinal  system  of  framing — interior 41 

21.  Profile,  half-breadth  and  body  plan 43 

22.  Spaces  in  a  cargo  vessel 45 

23.  Vessel  with  superstructures 45 

24.  Block  coefficients 54 

25.  Three-deck  vessel 70 

26.  Two-deck  vessel 71 

27.  Raised-quarterdeck  vessel 73 

28.  Raised-quarterdeck  with  extended  bridge 74 

29.  Short  raised-quarterdeck 75 

30.  Shelter-deck  vessel 76 

31.  Shelter-deck  vessel — profile 77 

32.  Well-deck  vessel 78 

33.  Vessel  with  superstructures 79 

34.  Shade-deck  vessel 80 

35.  Whaleback  steamer • .  81 

36.  Turret-deck  vessel 82 

37.  Turret-deck  vessel 83 

38.  Trunk-deck  vessel 84 

xv 


xvi  LIST  OF  ILLUSTRATIONS 


39.  Trunk-deck  vessel 85 

40.  Self-trimming  vessel 86 

41.  Cantilever  vessel 87 

42.  Cantilever  vessel 88 

43.  Corrugated  vessel 89 

44.  Tank  vessel 91 

45.  Tank  vessel 92 

46.  Steam  schooner 95 

47.  Awning-deck  vessel 97 

48.  Side-lever  engine 105 

49.  Oscillating  engine 106 

50.  Oscillating  geared  engine 107 

51.  Trunk  engine       .           108 

52.  Parsons  turbine 112 

53.  Yarrow  boiler 117 

54.  Semi-Diesel  engine 133 

55.  Displacement  scale 161 

56.  Immersion  curve 162 

57.  Dead-weight  scale 164 

58.  Freeboard  marks 172 

59.  Tonnage  length 181 

60.  Division  of  tonnage  length  and  depths 181 

61.  Measurements  of  transverse  section 182 

62.  Transverse  sections 183 

63.  Measurement  of  'tween-deck  spaces  .     .     .     .     .     .     .     .187 

64.  Propelling  power  deductions 195 

65.  Tonnage  calculation  sheet Insert  opposite  199 

66.  Tonnage  certificate 199 

67.  Propelling  power  deductions  compared 223 

68.  Lloyds'  Register — specimen  page 235 

69.  American  Register — specimen  page  of  "The  Record"      .     .  239 


PART  I 

CONSTRUCTION,  TYPES  AND  USES  OF 
MERCHANT  VESSELS 


CHAPTER  I 
METHODS  OF  PROPULSION 

In  a  study  of  the  carriers  of  maritime  commerce  the  distinction 
between  the  sailing  vessel  and  the  steamer  is  a  primary  concept. 
As  to  present-day  functions  of  these  craft,  the  circumstances 
which  led  to  the  decline  of  the  sailing  vessel,  and  the  qualities 
which  made  steam  preeminent  as  motive  power,  popular  opinion 
includes  many  misconceptions.  Steam  vessels  were  not  immedi- 
ately an  overwhelming  success,  did  not,  in  fact,  displace  the-  sail- 
ing vessel  as  fast  as  the  automobile  has  displaced  the  horse,  and, 
to  carry  the  analogy  further,  are  still  inferior  to  the  sailing  vessel 
under  some  circumstances,  as  the  motor  vehicle  is  to  the  horse  for 
a  limited  kind  of  service.  It  is  impossible  here  to  revise  these 
conceptions  by  a  history  of  the  development  of  vessels  but  this 
chapter  will  serve  to  distinguish  the  sailing  vessel  of  to-day  from 
its  predecessors  of  various  types,  to  explain  the  disappearance  of 
this  form  of  propulsion  and  to  indicate  its  few  remaining  uses. 
Thus  some  of  the  modern  characteristics  of  water  carriers  will 
be  emphasized  by  contrast  with  the  materials  and  methods  of  the 
past. 

CLASSIFICATION  OF  SAILING  VESSELS 

The  larger  sailing  vessels  may  be  grouped  in  classes  according 
to  "  rig  "  or  arrangement  of  sails,  the  number  of  masts,  and  the 
form  or  shape  of  hull.  The  principal  methods  of  rigging  are  the 
"  square  rig  "  and  the  "  fore-and-aft  rig/'  though  in  small  sailing 
vessels  peculiar  variations  have  been  introduced  by  custom  and 
convenience.  The  number  of  masts  has  tended  to  increase  with 
the  increased  size  of  vessels,  made  possible  by  improvements  in 
materials,  methods  of  construction  and  mechanical  handling,  until 
a  maximum  of  seven  has  been  reached.  The  subject  of  form  may 
be  dismissed  here  with  the  statement  that  it  developed  from  the 
bluff-bowed  vessel  with  a  "  beam  "  or  breadth  one- fourth  of  its 
length,  as  illustrated  in  the  English  vessels  in  the  West  Indian 

3 


MERCHANT  VESSELS 


trade  o£ '$ie;eaVty'  -nineteenth  century,  to  the  narrower  schooner 
and  "  clipper  "  ship,  with  concave  water  lines  at  the  bow,  beam 
only  one-fifth  or  one-sixth  the  length  and  relatively  great  breadth 
well  aft.  Other  developments  in  form  of  hull  are  discussed  later. 

A  *'  square-rigged "  vessel  is  one  with  the  yards  supporting 
square  sails  extending  across  the  masts,  approximately  equal 
lengths  of  yard  and  equal  sail  areas  extending  on  each  side.  The 
following  illustration  of  a  full-rigged  ship  shows  the  arrangement, 
some  subsidiary  sails  being  added  —  jibs,  staysails  and  spanker. 

In  the  "  fore-and-aft "  rig  the  yards  and  booms  do  not  cross 


Reproduced  by  permission  from  A.   M.   Knight,   "  Modern  Seamanship," 
Van  Nostrand  Co.,  N.   Y. 

FlG.    I. —  FULL  RIGGED  SHIP 

the  mast  but  extend  on  one  side  only,  the  sails  therefore  not  being 
square  but  tending  to  approach  a  triangular  form.  The  yards 
and  booms  move  with  one  end  resting  on  the  mast  as  a  pivot. 
Figure  2,  a  modern  schooner,  will  serve  as  an  illustration. 

Various  combinations  of  these  two  styles  of  rigging  on  vessels 
with  one  or  more  masts  produced  the  types :  ( I )  ship,  with  three 
or  more  masts,  all  square-rigged;  (2)  bark,  with  three  or  more 
masts,  all  masts  except  the  after-mast  square-rigged;  (3)  barken- 
tine,  with  three  or  more  masts,  the  two  after-masts  fore-and-aft 
rigged;  (4)  brig,  with  two  masts  both  square-rigged;  (5)  brigan- 


METHODS  OF  PROPULSION  5 

tine,  a  brig  without  a  square  mainsail;  (6)  the  sloop,  with  one 
mast  fore-and-aft  rigged;  (7)  the  schooner,  with  two  or  more 
masts  fore-and-aft  rigged.  The  last-named  is  the  sailing  vessel 
type  of  primary  importance  to-day. 

The  schooner  has  steadily  increased  in  size,  owing  largely  to 
the  introduction  of  machinery  for  hoisting  and  lowering  sails  and 


Reproduced  by  permission  from  Spear's  "  Story  of  the  American  Merchant  Marine," 

Macmillan,  1915 

FIG.  2. —  SCHOONER  —  Thomas  W.  Lawson 

anchors,  until  in  1902  the  Thomas  IV.  Lawson,  a  seven-masted 
steel  schooner  of  5218  tons  gross  register  was  launched.  This 
vessel  had  a  spread  of  43,000  square  yards  of  canvas  and  was 
manned  by  a  crew  of  18.  In  1890  an  i8oo-ton  vessel  with  five 
masts  was  considered  large  and  until  the  introduction  of  labor- 
saving  machinery  as  low  as  900  tons  marked  approximately  the 
limit  of  size.  The  schooner  has  usually  a  greater  proportionate 
beam  than  the  steamer,  a  high  freeboard  or  distance  from  water 
line  to  deck,  great  sheer  (curvature  of  deck)  forward,  and  an  un- 
obstructed deck  from  forecastle  to  bridge,  which  is  located  well 


6  MERCHANT  VESSELS 

aft  (see  illustration,  page  (5).  Both  the  square  and  fore-and-aft 
rig  have  advantages  in  different  winds  and  weathers,  but  the 
fore-and-aft  is  more  manageable,  thus  reducing  the  crew  and 
operating  expenses.  It  is  estimated  that  the  seven-masted 
schooner  described  above,  if  square-rigged,  would  require  a  crew 
of  40  men  to  handle  her  instead  of  a  crew  of  18. 

DECLINE  IN  IMPORTANCE  OF  THE  SAILING  VESSEL 

But  all   of   the   various   types   of   sailing  vessels   except   the 
schooner  have  been  driven  out  by  steamers,  and  the  usefulness  of 


Wor/d^'s  Merchant  Marine 

A/ef  /onnoge  of  Sf earners 

and  Sf" />ng  I/ess  f/s 


1910        1920 


even  this  form  is  exceedingly  limited.  This  elimination  of  the 
sailing  vessel  resulted,  not  from  the  unexceptionable  superiority 
of  the  steamer,  but  because  the  advantages  of  the  latter  out- 
weighed the  good  features  of  the  former.  Thus,  in  some  trades, 
such  as  to  the  Far  East,  the  competition  between  the  two  was 
keen  for  a  comparatively  long  time  and  only  great  improvements 
in  steam  propulsion  finally  gave  it  supremacy. 

By  reference  to  the  above  diagram  it  will  be  seen  that  the 
sailing  vessel,  as  regards  the  world's  merchant  marine,  could  not 
maintain  its  position  after  1880.  In  1860  sailing  vessels  con- 


METHODS  OF  PROPULSION  7 

tributed  89  per  cent  of  the  total  tonnage;  in  1870,  81  per  cent; 
in  1880,  71  per  cent;  and  by  1890,  only  53  per  cent.  At  the 
present  time  sailing  vessels  form  less  than  10  per  cent  of  the 
total  tonnage  of  the  world,  and  even  this  figure  exaggerates  their 
importance  because  of  the  many  insignificant  vessels  which  are 
included  to  form  this  aggregate. 

In  spite  of  the  impulse  which  the  development  of  early  steam 


- 

So// 

'  <7/7<y  Steam  Tonn 
of  ffa 
United  States 

age 

\ 

/ 

/ 

f 

v 

/ 

X 

V 

/ 

+r 

^ 

—  «l/t 

/ 

^^^ 

~~  

rr^i^ 

^-^ 

«.  —  -  —  • 

,_—  •  -  — 

— 

fTC** 

^^ 

£0         I&30         1840        1850        I860         1870         I860         1890         1900         1^0         19 

FIG.  4 

navigation  received  in  the  United  States  we  continued  longer  than 
foreigners  to  attempt  to  use  the  sailing  vessel  as  a  competitor  of 
steam,  as  illustrated  by  the  above  diagram.  Thus,  in  world 
commerce  in  1900,  32  per  cent  of  the  tonnage  was  sail,  while  over 
49  per  cent  of  American  tonnage  was  still  propelled  in  this  man- 
ner. To  put  it  in  another  way,  the  world  fleet  was  composed  al- 
most equally  of  steam  and  sail  tonnage  shortly  after  1880,  while 
American  steam  tonnage  did  not  equal  sail  until  nearly  1899. 
The  facts  are  equally  well  stated  by  saying  that  the  sail  tonnage 
of  the  United  States  has  declined  more  slowly  than  that  of  the 
world,  but  wie  have  not  kept  pace  in  the  acquisition  of  steam 
vessels. 


MERCHANT  VESSELS 


ADVANTAGES  OF  STEAM  OVER  SAIL 

It  will  throw  some  light  upon  the  nature  of  present-day  com- 
merce to  indicate  the  reasons  for  the  supplanting  of  sail  by  steam. 

i.  The  Superior  Regularity  of  Steam-Propelled  Vessels. —  In 
the  early  days  of  steam  vessels  they  were  subject  to  great  handi- 
caps because  of  the  inferior  nature  of  the  engines  utilized  for  the 
work  and  the  consequent  heavy  consumption  of  fuel.  It  is  a 
mistake  to  suppose  that  the  steamer  everywhere  outstripped  the 
sailing  vessel;  the  latter  held  its  own  on  some  routes  for  years. 
But  one  manifest  advantage  possessed  by  the  steamer,  in  spite 
of  its  deficiencies,  was  that  of  regularity.  A  sailing  vessel  might 
make  the  voyage  from  London  to  Australia  in  60  days  with  a  good 
passage,  but,  on  the  other  hand,  it  was  equally  likely  that  the  trip 
would  consume  half  again  as  much  time.  The  date  of  the  sailing 
vessel's  arrival  was  purely  a  matter  of  conjecture,  and  commercial 
projects  .based  upon  it  were  therefore  merely  tentative  in  nature. 
As  an  illustration,  in  the  cotton  business  45  years  ago  the  con- 
tracts were  entirely  for  delivering  the  product  "  on  the  spot  "  and 
"on  arrival."  A  contract  for  delivery  by  some  definite  future 
date,  such  as  now  constitutes  the  majority  of  transactions,  was  an 
impossibility,  because  of  transportation  conditions.  A  little  later 
it  was  practicable  to  make  a  future  contract  specifying  delivery 
within  two  named  months  and  at  present  a  merchant  can  name 
the  day  of  delivery.  For  the  same  reason,  contracting  for  vessel 
space  in  advance,  an  almost  universal  practice  now,  was  beset 
with  many  difficulties.  As  a  matter  of  fact,  in  those  early  days, 
a  steam  vessel  with  a  speed  of  8  or  ,9  knots  was  superior  to  a 
sailing  vessel  on  the  average,  although  the  latter  might  attain 
double  that  speed.  Too  much  importance  can  hardly  be  assigned 
to  this  factor  of  regularity,  for  steamship  men  testified  in  an  in- 
vestigation of  rates  and  practices  in  1913  that  in  modern  com- 
merce the  primary  factors  of  importance  were  regularity  and  de- 
pendability of  service  and  rates.  A  glance  at  the  map  on  page 
10  will  show  the  difficulties  experienced  by  the  sailing  vessel. 
The  larger  and  more  important  sailing  routes  of  the  world  are 
shown  here  and  some  of  the  important  constant  winds,  it  being 
impossible  on  a  map  of  this  size  to  indicate  all  the  routes  or  even 
more  than  a  few  of  the  winds.  The  map  is  sufficient  to  show, 
however,  that  the  sailing  vessel  was  limited  in  its  routes  by  the 


METHODS  OF  PROPULSION  9 

direction  of  the  winds;  that  the  seasons  of  the  year  might  affect 
the  length  of  the  voyage,  as  for  instance  in  the  Indian  Ocean, 
where  the  space  on  the  map  is  insufficient  to  show  the  well-known 
seasonal  winds;  that  deviations  from  direct  paths  were  necessary 
to  take  advantage  of  favorable  winds,  as  for  instance  the  routes 
between  the  4Oth  and  6oth  parallel  south  to  obtain  the  benefit 
of  the  westerly  winds,  or  on  a  voyage  from  Panama  in  a  northerly, 
southerly,  or  westerly  direction  working  south  and  west  as  far 
as  the  Galapagos  Islands  before  obtaining  favorable  winds  and 
currents,  or  bound  from  New  York"  to  the  West  Coast  of  South 
America  via  Magellan  the  deviation  eastward  nearly  to  the 
Canary  Islands  to  obtain  the  assistance  of  the  trade  winds  and 
pass  Cape  St.  Roque,  Brazil;  that  deviations  were  necessary  to 
avoid  unfavorable  winds  and  currents  as  in  circling  the  southeast 
trade  winds  in  the  South  Atlantic ;  that  calms  might  be  experienced 
anywhere  and  were  particularly  imminent  in  certain  localities ;  and 
so  on,  innumerable  illustrations  being  available  in  books  contain- 
ing sailing  directions.  The  map  on  page  10  shows  some  of 
these  sailing  routes. 

2.  The  Higher  Average  Speed  of  the  Steamship. —  In  many 
trades  speed  is  a  highly  important  transportation  quality,  as,  for 
instance,  in  the  transportation  of  perishable  commodities  and  the 
trade  in  highly  competitive  products  where  service  plays  a  large 
part  in  the  price.  The  steamship  gradually  demonstrated  that 
on  the  whole  it  would  not  only  be  more  punctual,  but  would  give 
steadily  superior  service  as  far  as  the  element  of  time  was  in- 
volved. Subsequent  developments  of  engines,  boilers,  propellers, 
etc.,  merely  accentuated  this  superiority.  Thus  the  voyage  from 
Panama  to  San  Francisco  is  performed  by  a  Q-knot  steam  freighter 
in  15  days,  while  the  average  for  a  sailing  vessel  is  37  days.  From 
New  York  to  San  Francisco  via  Straits  of  Magellan  took  a  sailing 
vessel  140  days  while  a  steamer  of  9-knots  could  make  the  distance 
in  approximately  60  days.  Interest  on  the  money  involved  in  a 
shipment  may  be  an  important  consideration.  Thus,  silk  ship- 
ments from  Japan  may  involve  interest  charges  on  a  sum  as  large 
as  a  $1,000,000  and  in  many  trades  the  shipments  will  involve  in- 
terest on  sums  ranging  from  $25,000  to  $200,000.  Obviously 
sailing  vessels  under  such  conditions  fall  in  the  class  of  expensive 
luxuries  rather  than  economical  carriers. 


METHODS  OF  PROPULSION  u 

3.  Greater  Efficiency  of  the  Steamship. —  While  at  first  the 
steamship  was  a  voracious  consumer  of  fuel  and  on  early  voyages 
the  vessel  not  uncommonly  was  compelled  to  utilize  the  spars  and 
woodwork  for  this  purpose,  it  subsequently  became  considerably 
more    economical.     Furthermore,    the    fuel    difficulty    was    very 
greatly  reduced  by  the  establishment  of  numerous  coaling  stations 
in  all  parts  of  the  world.     The  steamer  attained  superiority  in 
the  long  distance  trades,  however,  only  after  considerable  effort. 
It  is  popularly  assumed  for  statistical  purposes  that,  considering 
the  superior  efficiency  of   the  steamer,  sail   tonnage  should  be 
divided  by  four  to  put  it  on«a  basis  with  steam. 

4.  The  Development  of  Canals  an  Additional  Handicap  to 
Sailing    Vessels. — The    Suez    Canal,    for    example,    which    was 
opened  for  traffic  in   1869,  reduced  the  distance  between  New 
York  and  Bombay  by  3400  miles,  and  the  distance  between  New 
York  and  Hong  Kong  by  nearly  3000  miles,  yet  the  absence  of 
regular  winds  in  the  Red  Sea  prevented  the  sailing  vessel  from 
taking  advantage  of  this  route.     The  same  deficiency  in  Panama 
Bay  restricts  the  use  of  this  waterway  by  sailing  vessels. 

The  sailing  vessel  had  some  points  in  its  favor,  however, 
and  these  have  enabled  it  still  to  remain  in  some  trades  where  it 
has  .special  uses.  These  favorable  features  are  ( I )  motive  power 
without  cost;  (2)  a  large  net  cargo,  no  space  being  occupied  by 
boilers,  engines,  coal  bunkers,  and  shaft  which  in  a  steamer  con- 
sume from  one- fourth  to  one-third  the  hull  capacity ;  (3)  a  smaller 
minimum  crew  with  a  few  highly  skilled  men.  A  sailing  vessel 
of  2400  net  tons  might  require  a  crew  of  34  of  whom  22  are  sea- 
men while  a  steamer  of  similar  size  shipped  a  crew  of  38,  of  whom 
1 1  were  seamen  and  17  engineers,  firemen,  and  coal  passers.  On  a 
large  and  slow  steam  vessel  the  crew  may  average  as  low  as  one 
man  per  100  tons  net  register  but  the  average  for  a  similar  sail- 
ing vessel  may  be  even  lower.  One  writer  has  described  the 
struggle  between  sail  and  steam,  as  "  a^  competition  between  low 
costs  and  low  efficiency,  and  high  cost  and  high  efficiency,  and  higrT 
emciency  is  winning." 

PRESENT  USES  OF  SAILING  VESSELS 

i.  The  sailing  vessel  still  remains  somewhat  of  a  factor  in  con- 
nection with  certain  trades,  for  example,  the  coasting  trade,  which 


12 


MERCHANT  VESSELS 


is  not  readily  organized.  Here  a  definite  amount  of  tonnage  is 
not  regularly  available  and  the  return  is  not  large  enough  to  war- 
rant the  investment  of  the  additional  capital  required  for  a  steam- 
ship or  the  expenditure  of  coal  necessary  to  call  where  cargo  is 
uncertain.  Thus,  in  the  coastwise  trade  the  steamers  are  largely 
engaged  as  combination  passenger  and  freight  liners  and  the  tramp 
freighting  is  relinquished  to  sailing  vessels  and  towed  barges.  On 
the  Pacific  Coast  large  wooden  schooners  are  considerably  used 
but  often  equipped  with  auxiliary  steam  or  gas  engines.  The 
Great  Lakes  trade  is  not  adapted  to  the  use  of  sailing  vessels. 
The  vice  president  and  general  manager  of  the  Clyde  and  Mal- 
lory  Steamship  Companies  testified  in  an  investigation  that  not  a 
single  port  on  the  Atlantic  Coast  would,  with  the  business  orig- 
inating at  the  port  and  without  feeding  from  the  interior  by 
railroad  lines,  maintain  even  temporarily  the  services  now  fur- 
nished by  established  lines  of  steamers.  The  majority  of  sailing 
vessels  are  employed  on  the  Atlantic  and  Gulf  Coasts  and  are 
operated  as  tramps,  being  chartered  for  a  voyage  or  a  longer 
period,  the  illustration  of  the  Thomas  W .  Lawson  on  page  5,  show- 
ing the  highest  development  of  the  schooner.  This  vessel  was 
used  for  the  carriage  of  coal  between  Norfolk  and  New  England 
ports,  having  a  capacity  of  about  8000  tons  of  this  product. 
Eventually,  because  of  her  deep  draft,  she  was  removed  from  this 
trade  and  transformed  into  an  oil  carrier,  because  unable  to  load 
her  full  cargo  at  either  Philadelphia  or  Baltimore.  This  vessel 

SAIL  TONNAGE  OF  UNITED  STATES,  1906  AND  1916 


1906 


1916 


Tonnage 
Class 


Number 


Tonnage  Number          Tonnage 


5-  49 

4,255 

72,734 

i,337 

26,619 

50-  99 

685 

47.731 

335 

22,989 

100-  199 

353 

51,219 

180 

26,005 

200-  299 

242 

60,491 

118 

29,484 

300-  399 

205 

71,241 

90 

3IJ46 

400-  499 

224 

100,796 

9i 

40,927 

500-  999 

718 

517,208 

502 

371,688 

1000-2499 

388 

581,046 

303 

465,362 

2500-4999 

57 

181,465 

43 

141,827 

5000  &  up 

4 

20,345 

3 

15,127 

Total 

7,131 

1,704,276 

3,002 

i,i7i,i74 

Average 

239 

390 

METHODS  OF  PROPULSION  13 

was  a  seven-masted,  double-bottom  steel  schooner  of  5218  tons 
gross  register  and  4914  tons  net.  The  lower  masts  and  bowsprit 
were  constructed  of  steel  tubes. 

The  above  table,  taken  from  the  Census  Report  of  1916, 
brings  out  several  interesting  facts  regarding  the  sail  tonnage 
of  the  United  States.  While  the  number  of  vessels  declined  by 
over  57  per  cent,  the  total  gross  tonnage  declined  by  only  31  per 
cent;  while  great  decreases  in  tonnage  are  apparent  in  vessels 
of  up  to  500  tons  gross,  the  decreases  are  less  noticeable  in  vessels 
of  over  500  tons.  In  other  words,  such  sailing  vessels  as  tend  to 
remain  in  operation  are  those  of  greater  size. 

2.  The  use  of  sailing  vessels  may  be  temporarily  increased  by 
changes   in  conditions  of  construction  and  operation.     Thus  a 
period  of  insufficiency  of  steam  tonnage  may  make  the  sailing 
vessel  temporarily  a  profitable  enterprise,  so  profitable  at  the  time 
as  to  more  than  counterbalance  the  possible  future  difference  in 
usefulness.     Thus  the  period  of  the  World  War  saw  steam  ton- 
nage at  a  premium  and  absolutely  necessary  for  navigating  the 
war  zone,  while  sailing  vessels  were  temporarily  utilized  for  per- 
forming work  ordinarily  done  by  the  steamer.     The  United  States 
Government,  for  example,  put  steamers  on  the  route  to  France 
and  utilized  French  sailing  vessels  to  supply  the  deficiency  in 
other  trades  so  created.     The  period  1899-1900  saw  a  revival  of 
the  sailing  vessel  because  of  the  scarcity  of  ships,  the  high  ocean 
freight  rates,  and  the  high  price  of  steel. 

3.  The  sailing  vessel  may  be  a  factor  in  any  trade  where  the 
cost  of  investment  is  a  highly  important  consideration.     In  some 
lines  of  business  the  return  would  not  be  sufficient  to  cover  the 
loss  of  interest  on  an  expensive  vessel,  and  the  wooden  sailing 
vessel  may  be  built  for  perhaps  20  per  cent  less  than  one  of  another 
type. 

4.  A  similar  use  is  sometimes  found  for  the  schooner  in  ocean 
traffic  with  countries  where  the  trade  is  very  irregular  and  poorly 
developed.     The  sailing  vessel  may  provide  a  cheap  method  of 
attempting  to  develop  a  regular  trade. 

5.  In  the  carriage  of  bulk  cargoes  the  sailing  vessel  still  remains 
an  agency  of  some  importance.     Coal,  lumber,  grain,  nitrate  of 
soda,  and  sugar  have  always  been  considered  particularly  suitable 
cargoes  for  sailing  vessels.     One  of  the  few  regular  sailing  lines 
from  the  United  States  is  the  Benner  Line  to  Porto  Rico,  of  whose 


MERCHANT  VESSELS 


vo 

ON 


5 

en 
S 


a 

c  *o 
rt  c 


t? «— ' 

•*->    tn 
O    en 


.  .     .  ON 

to  tx  O  to  i— i  to  ^* 

H^OO^OO^  o^oo^  ix  vq^ 

•-T  t-T  rf-vo"  O~  rf  O\ 

T?       i-T       of  oo" 


rf  ON  Tj-  M   I-H  m 
\r>  o\  t^  \r>  in  >-> 

fO        O          000 

vo"      in      co  i-T 


^  ^     ^ 

fO    I   of     !   -^f  ON 

$  -a  •? 


t>x  •    O  •  tO  ON  1-1 

CO  •  VO  •  01   tx  O 

ON  •  co  •  to  i-i  q^ 

of  "  t-f  '  to 


tO  fO  01 


oo" 

00 


ONOO         Tf 

h-4  ^S^ 


tx  ON^O  01 
ON  ONOI 
1-1  01 


tooo 
txco 

tx  ON 


(N 


f-i  O  01 
O 


O  VO    tX  •-"    01 
OO    -i          ON 


*O     -en 

§§ 


ON 


CO  ONOO  to  CO  tX  10 

ONVO   O  ON  O   01  ON 

q_  »o  1-1  oo  vo  oo  o 

oo"  of  «-T  ~*  tf\o  to 

to      00  ^  co  O  ON 

VO        vO         ^f  »-"  00 

of  of  to 


VO 


I  VO    *->   ON  Tf  to  Ol  tv 

OJ  VO    to  O\  04    tx  f^. 

°l  *"t  *>  ""t  °!  Q 

**    O\  rf  CO  of  O" 

VO          to        OO  •"• 

00  01          w  C^ 


-  fc  F3      - 


c  ovc  ««  JO  «       -M 

|l'S|i|  ^ 

<^^^^^ 


METHODS  OF  PROPULSION  15 

exports  sugar  is  approximately  three-fifths  in  value.  A  large  por- 
tion of  the  nitrate  trade  from  Chile  to  Europe  and  the  Atlantic 
ports  of  the  United  States  was  formerly  handled  by  sailing  vessels 
but  this  business  has  been  extensively  invaded  by  the  steamer. 
Other  illustrations  of  the  use  of  the  sailing  vessel  are  found  in 
the  jute  trade  of  India,  the  grain  trade  of  California  and  British 
Columbia,  and  the  transport  of  nickel  ore  from  New  Caledonia. 
Sailing  vessels,  even  after  the  demonstrated  superiority  of  steam, 
continued  to  carry  much  of  the  coal  and  lumber  on  the  Atlantic 
coast ;  in  the  coal  trade  the  schooner  barge  has  come  into  promin- 
ence. There  are  still  numerous  important  lumber  fleets  on  the. 
Pacific  Coast  and  this  is  the  principal  occupation  of  the  sailing 
vessel  in  this  region ;  some  experienced  maritime  men  still  believe 
that  a  wooden  five-masted  sailing  schooner,  with  single  deck  and 
a  carrying  capacity  of  approximately  1,500,000  feet  of  lumber  is 
the  most  economical  vessel  in  this  business,  because  of  safety 
without  ballast,  cheap  motive  power,  and  lower  construction  cost. 
Bulk  products  have  continued  to  be  carried  by  sailing  vessels  be- 
cause they  are  usually  shipped  as  full  vessel  cargoes,  do  not  re- 
quire rapid  transportation,  and  prompt  delivery  is  a  negligible 
factor.  It  was  formerly  believed  that  in  some  of  the  long-dis- 
tance trades,  as  for  instance  to  Australia  and  to  the  Orient,  the 
sailing  vessel  would  always  remain  a  competitor  of  considerable 
importance,  but  experience  to  date  has  not  verified  this  opinion. 
Wherever  the  business  is  regular  in  character  the  steamer  has 
found  extensive  employment. 

6.  The  system  of  bounties  in  vogue  in  certain  foreign  countries 
to  some  extent  renders  possible  the  continued  competition  of  sail- 
ing vessels. 

The  following  table  shows  the  distribution  of  steam  and  sail 
tonnage  of  the  seagoing  merchant  vessel  (500  gross  tons  and 
over)  of  the  United  States,  as  reported  by  the  United  States 
Shipping  Board  on  February  28,  1919. 


Number 

Gross  Tonnage 

Steamers  ...             ...          .            

i  ^8 

4  ^QO.47Q 

Tankers  

174- 

Q^O,I7^ 

Sailing  vessels   

^QO 

442,^7 

Schooner  barges  

^4 

^84,60* 

Total    . 

2,2t;6 

6,l67,704 

16  MERCHANT  VESSELS 

Of  the  above  390  sailing  vessels  157  were  acquired  between 
July,  1914,  and  February,  1919.  One  hundred  were  of  new  con- 
struction, 38  obtained  by  foreign  purchase,  12  converted  from 
other  types,  and  7  seized  from  Germany.  The  losses  to  sailing 
vessels  during  this  period,  however,  were  even  greater  than  the 
acquisitions,  totaling  251  vessels  of  270,908  gross  tons,  mostly  by 
marine  risks. 

To  summarize,  then,  the  fore-and-aft  rigged  vessel  in  the  form 
of  the  schooner  alone  of  the  various  sailing  vessels  survived  the 
competition  of  steam,  and  a  considerable  increase  in  its  size  and 
the  development  of  mechanical  aids  were  necessary  for  economical 
operation.  The  expensive  but  efficient  steamer  reduced  the  pro- 
portion of  sail  from  90  to  10  per  cent  of  the  world's  tonnage; 
though  this  took  place  more  slowly  in  the  United  States  than  else- 
where. The  former  had  superior  regularity,  higher  average  speed, 
greater  efficiency,  and  was  helped  and  not  hindered  by  canals. 
The  latter  had  some  advantageous  features  but  these  enabled  it 
to  remain  only  under  particular  circumstances,  namely,  (i)  in 
the  coasting  trade  which  is  not  readily  organized,  (2)  temporary 
changes  in  constructing  and  operating  conditions,  (3)  where  cost 
of  investment  is  primarily  important,  (4)  in  irregular  and  poorly 
developed  ocean  traffic,  and  (5)  in  the  carriage  of  bulk  cargoes 
in  the  coastwise  business  and  on  a  few  ocean  routes. 

REFERENCES 

1.  O'DONNELL,  E.  E.r     The  Merchant  Marine  Manual.    The  Yachts- 

man's Guide.  Boston,  1918.  Pp.  58-73.  (On  the  various 
types  of  sailing  vessels.) 

2.  JOHNSON,  E.  R.,  and  HUEBNER,  G.  G. :    Principles  of  Ocean  Trans- 

portation. D.  Appleton  &  Co.,  New  York,  1918.  Chap.  I. 
(On  the  various  types  of  sailing  vessels.)  Chap.  V.  (On 
ocean  routes.) 

3.  KIRKALDY,  A.  W.:     British  Shipping.     Paul,  Trench  Triibner  & 

Co.,  London  and  New  York,  1914.  Chaps.  V,  VI,  VII,  and 
VIII.  (On  the  gradual  ascendancy  of  the  steamer.) 

4.  SMITH,  J.  R.:     Organisation  of  Ocean  Commerce.     Publications 

of  University  of  Pennsylvania,  Series  in  Political  Economy  and 
Public  Law,  Philadelphia,  1905.  Chap.  VII.  (On  the  gradual 
ascendancy  of  the  steamer.)  Chap.  VII.  (On  the  sailing 
routes  of  the  world.) 


METHODS  OF  PROPULSION  17 

5.  JOHNSON,  E.  R. :    "  Panama  Canal  Traffic  and  Tolls,"  report  to 

U.  S.  Secretary  of  War,  1912.  Washington,  D.  C,  1912.  Ap- 
pendix I.  (On  industrial  and  commercial  value  of  the  Isthmian 
Canal.)  Chap.  IX.  (On  the  handicap  to  sailing  vessels  of 
canal  routes.) 

6.  Reports   of  the   U.   S.   Commissioner   of   Navigation.    Annually. 

Washington,  D.  C.  (Giving  statistics  of  the  American  mer- 
chant marine.) 

7.  Pacific  Marine  Review,  February,  1919,  pp.  io8-iu.     (Description 

and  diagrams  of  sailing-vessel  rigs.) 


CHAPTER  II 
MATERIALS  OF  CONSTRUCTION 

The  object  of  this  chapter  is  to  classify  vessels  with  reference  to 
the  materials  from  which  they  are  commonly  constructed.  These 
include  principally  wood,  iron,  steel,  and  concrete,  and  by  a  com- 
bination of  steel  and  wood  the  "  composite  "  ship  is  obtained.  In 
order  to  compare  intelligently  the  vessels  produced  from  these 
materials  it  is  necessary  to  examine  briefly  the  principal  parts  of 
the  earliest  type  of  vessel  —  the  wooden  ship.  This  will  also  serve 
later  as  a  basis  and  a  background  for  the  description  of  the 
modern  cargo  carrier  —  the  steel  vessel.  Since  it  is  impossible 
here  to  scrutinize  the  engineering  and  architectural  details  of  the 
wooden  ship  the  description  and  illustrations  will  be  reduced  to 
their  simplest  elements,  omitting  many  features  which  are  un- 
essential for  present  purposes.  Numbered  references  after  the 
terms  used  are  to  the  diagram  on  page  20. 

PRINCIPAL  PARTS  OF  A  WOODEN  SHIP 

The  keel  (i)  is  the  foundation  or  backbone  of  the  vessel.  The 
various  other  members  of  the  vessel  are  all,  in  a  sense,  supported 
by  the  keel.  So  important  is  this  part  that  it  is  protected  against 
the  damages  of  grounding  by  a  shoe  (2)  lightly  bolted  to  its 
bottom,  which  may  be  torn  off  without  material  injury  to  the 
keel  itself.  At  the  bow  end  of  the  keel  is  placed  the  stem  (3), 
which  is  fastened  to  the  keel  by  a  hook-scarf,  a  method  of  dove- 
tailing which  prevents  pulling  apart  longitudinally.  At  the  stern 
end  of  the  keel  is  fastened  the  sternpost  (4)  by  tenon  and  mortise. 
Next  is  placed  in  position  the  larger  portion  of  the  '*  ribs  "  of 
the  ship,  designated  the  "  square-frame,"  and  including  all  the 
individual  frames  (5)  or  ribs  which  are  fastened  to  the  keel. 
Some  others  at  the  bow  and  stern  must  be  otherwise  attached  and 
supported.  These  U-shaped  frames  are  raised  from  the  ground 
by  a  derrick  and  placed  in  position  across  the  keel.  Each  frame 

18 


MATERIALS  OF  CONSTRUCTION  19 

is  constructed  from  several  frame-timbers  joined  together  and 
the  joints  are  arranged  so  that  no  straight  joining  line  runs  the 
length  of  the  keel;  to  make  the  joints  all  at  the  exact  center  of 
the  keel  would  be  unnecessarily  to  impart  an  element  of  weak- 
ness. Above  the  keel,  parallel  with  it,  and  resting  on  the  frames 
is  laid  the  keelson  (6),  which  is  fastened  by  bolts  through  itself, 
the  frames,  and  the  keel.  It  gives  additional  strength  to  the  union 
of  keel  and  frames. 

As  the  vessel  becomes  sharper  toward  the  stem  and  stern  it  is 
impossible  to  attach  all  the  ribs  to  the  keel  and  these  frames 
called  forward-cants  and  after  cants  (7)  rest  upon  a  mass  of 
timber  called  the  forward  and  after  dead-wood  (8),  which  is 
bolted  to  the  stem,  keel,  and  sternpost.  The  cants  gradually  in- 
cline toward  the  extremities  of  the  vessel  from  a  position  at  right 
angles  to  the  deck  to  parallel  with  it,  and  give  the  curve  to  the 
vessel  at  the  bow  and  stern. 

The  skeleton  of  the  vessel  is  now  in  existence  and  is  ready 
to  be  covered.  Beginning  at  the  keel  the  outside  planking  (9)  is 
put  on  longitudinally,  and  inside  the  frames  the  ceiling  (10)  oc- 
cupies a  similar  position.  Individual  planks  of  common  refer- 
ence are  given  names,  such  as  the  garboard  strakes  (the  first  two 
planks  to  be  worked  on  the  outside  of  the  frame),  and  the  sheer 
strakes  (the  top  full  course  of  planks  at  the  deck  level).  Air  is 
admitted  between  planking  and  ceiling  by  air  strakes,  which  are 
merely  spaces  left  in  the  ceiling.  Before  the  ceiling  can  be  worked 
up  to  the  upper  deck  the  intervening  decks  have  to  be  provided 
for. 

Heavy  pieces  of  timber  called  beams  (11)  are  laid  transversely 
across  the  ship  between  and  attached  to  the  frames.  These  sup- 
port and  prevent  the  collapse  of  the  sides  of  the  ship  and  furnish 
a  basis  for  laying  a  deck  (12).  They  are  also  supported  by 
stanchions  (20).  Running  fore  and  aft  from  beam  to  beam  are 
shorter  pieces  of  timber  called  cartings  (13).  These  support  the 
deck  at  places  where  openings  must  be  cut.  Running  transversely 
between  the  beams  are  smaller  timbers,  ledges  (14),  which  are 
let  into  the  carlings.  The  terminations  of  the  beams  are  ree'n- 
forced  by  knees  (15),  natural  growths  of  timber  forming  nearly 
a  right  angle,  which  are  used  as  braces.  Openings  called  hatches 
(16)  are  let  into  the  decks  for  the  purpose  of  loading  and  un- 
loading cargo,  etc.,  and  framed  by  fore-and-aft  timbers  called 


20 


MERCHANT  VESSELS 


hatch  coamings  (17).  The  hatches  are  shown  uncovered  in  the 
illustrations.  At  the  stern  may  be  seen  the  rudder  (18),  and 
above  the  top  deck  the  bulwarks  (19). 


FlG.  6. —  PRINCIPAL  PARTS   OF  A   WOODEN   VESSEL 


DISADVANTAGES  OF  WOOD  AS  A  SHIPBUILDING  MATERIAL 

Wood  was  the  natural  material  for  the  construction  of  vessels 
because  of  its  abundance,  the  ease  with  which  it  could  be  worked, 
and  its  buoyancy.  In  the  United  States  it  continued  to  be  used 
as  a  material  even  after  other  nations  had  begun  the  change  to 
iron.  The  early  steamers  were  wooden  vessels,  and  it  was  even 
for  a  time  contended  that  iron  vessels  would  not  float.  But 
with  the  development  of  steam  power  and  the  gradual  increase 
in  the  size  of  vessels,  due  to  the  discovery  that  large  units  could 
be  more  economically  operated  than  small,  the  defects  of  wood 
as  a  material  became  more  and  more  apparent.  These  were  as 
follows : 

I.  Except  in  the  United  States,  wood  became  increasingly 


MATERIALS  OF  CONSTRUCTION  21 

cult  to  obtain.     Soft  wood  would  not  yield  first-class  results,  and 
oak  was  becoming  expensive. 

2.  The  iron  vessel,  despite  the  high  specific  gravity  of  the  ma- 
terial, was  lighter  than  a  wooden  vessel.     While  the  individual 
plates  would  sink,  if  placed  in  water,  the  ship  had  not  the  same 
specific  gravity  as  its  material,  a  large  part  of  its  cubic  contents 
being  air.     A  vessel  will  float  as  long  as  its  enclosed  water-tight 
volume,  expressed  in  cubic  feet,  is  greater  than  its  total  weight 
in_tons  multiplied  bv  ,35,  since  35  cubic  feet  of  sea  water  weighs 
i  ton.     To  put  it  in  another  way,  35  cubic  feet  of  sea  water  will 
support  I   ton  of  35  cubic  feet  capacity.     Therefore,  the  ratio 
of  the  cubic  capacity  of  the  vessel  to  the  unit  35  cubic  feet  deter- 
mines the  maximum  weight  of  a  floating  vessel.     In  the  early 
wooden  vessels  the  weight  of  the  hull  and  fittings  aggregated 
from  35  to  45  per  cent  of  the  total  displacement,  whereas  in  an 
iron  vessel  of  the  same  size  these  two  contributed  only  from 
25  to  35  Per  cent  of  the  total  displacement.     By  the  utilization 
of  iron  there  was  a  saving  of  approximately  one-fourth  in  the 
weight  of  the  hull,  and  this  in  spite  of  the  fact  that  these  more 
or  less  experimental  vessels  contained  far  more  metal  than  was 
afterward  found  necessary. 

3.  To  attain   equal   strength  the  wooden   ship   required   keel, 
beams  and  frame  of  far  greater  thickness,  one  inch  of  iron  be- 
ing much  stronger  than  one  inch  of  wood.     This  meant  that  the 
iron  vessel  had  more  carrying  space  and  carrying  power  in  pro- 
portion to  its  outside  dimensions  and,  consequently,  a  greater 
earning  power.     As  shown  by  the  figures  above,  of  every  100  tons 
displacement  in  the  wooden  ship  about  40  tons  were  hull  and  fit- 
tings and  about  60  tons  cargo.     In  the  iron  vessel  similarly  loaded 
of  every  100  tons  displacement  about  30  tons  were  hull  and  fit- 
tings and  70  tons  cargo. 

4.  The  iron  vessel  was  apparently  capable  of  indefinite  expan- 
sion in  size,  and  in  fact  in  our  time  metal  vessels  have  been 
limited  in  size  more  by  canals  and  terminal  facilities  than  by  in- 
herent engineering  difficulties.     The  wooden  vessel,  on  the  other 
hand,  owing  to  the  nature  of  the  material,  was  practically  limited 
to  a  length  of  300  feet  *  and  the  most  successful  were  not  much 
more  than  200  feet  long. 

1  Compare  with  the  Minnesota,  1905,  622  teet;  the  Bismarck,  1914,  912 
feet. 


22 


MERCHANT  VESSELS 


5.  The  use  of  iron  increased  the  structural  strength  even  ir- 
respective of  size.  About  1834  the  Garry  Owen,  an  early  iron 
vessel,  was  driven  ashore  with  many  wooden  vessels  without 
serious  injury,  while  the  others  were  almost  total  losses;  and  in 
1843  the  Great  Britain,  an  iron  vessel  of  then  great  size,  stranded 
on  the  Irish  coast  and  remained  on  the  beach  all  winter  with  but 
little  injury.  These  cases  were  at  the  time  convincing  object 


JDI 

Z 

i          * 

i 
1 

1 

3 

i 

4 

t 

6 

'1- 

* 

1 

I 

1 

Z 

3                  < 

1 

^^ 

L                    -J                           ' 

FlG.   7. —  VESSEL  STRESSES   IN    STILL  WATER 

lessons  of  the  value  of  iron  as  a  shipbuilding  material.  Even 
under  ordinary  circumstances  a  vessel  is  subjected  to  stresses  of 
many  kinds,  tending  to  produce  distortions  called  "  strains."  The 
above  illustration  shows  a  cargo  vessel  floating  light  and 
divided  into  imaginary  parts  and,  since  the  parts  themselves  have 
weight  and  buoyancy,  the  existent  stresses  even  under  these  con- 
ditions. 

There  are,  therefore,  vertical  forces  tending  to  bend  and  break 
the  keel,  to  crack  stanchions  of  wood,  loosen  the  frames  and 
planking.  By  the  loading  of  cargo  these  stresses  are  increased. 

At  sea  other  stresses  appear.  The  two  following  illustrations 
show  those  developed  by  the  actions  of  the  waves. 


MATERIALS  OF  CONSTRUCTION  23 

In  one  case,  the  vessel  is  fully  supported  amidships  but  with- 
out support  at  the  extremities  with  consequent  tendency  to  "  hog." 
In  the  other,  the  extremities  rest  upon  the  waves  but  the  integrity 
of  the  middle  portion  depends  largely  upon  the  strength  of  ma- 
terial and  workmanship  with  consequent  tendency  to  "  sag." 

By  rolling  in  the  waves,  furthermore,  there  is  a  tendency  for  a 
vessel  to  alter  its  transverse  form,  as  in  the  following  illustra- 


FlG.   8. —  VESSEL  STRESSES  IN   WAVES 

tion.  This  tears  the  stanchions  away  from  the  keel,  distorts 
the  position  of  the  frame,  separates  the  beams  from  the  frame, 
or  separates  the  several  portions  of  the  frame,  destroys  the  align- 
ment of  stem,  stern,  and  keel,  and  opens  gaps  in  the  planking  or 
covering. 

It  would  be  possible  to  enumerate  other  stresses  to  which  ves- 
sels are  subject,  such  as  the  head  resistance  at  high  speed,  the 
pounding  on  the  bottom  at  the  fore  part  of  the  vessel,  and  the 
stresses  of  loading,  but  the  foregoing  is  sufficient  to  partially  il- 
lustrate the  difficulty  of  attaining  satisfactory  results  in  wooden 
vessels  of  great  size. 

6.  The  iron  vessel  was  better  suited  to  resist  the  constantly  in- 


24  MERCHANT  VESSELS 

creasing  weight  and  vibration  accompanying  the  development  in 
size  of  the  marine  engine.  This  vibration  subsequently  became 
an  important  engineering  problem  even  in  connection  with  metal 
vessels. 

7.  The  metal  vessel  was  superior  in  point  of  view  of  fire-resist- 
ing qualities.  In  1909  the  Celtic,  a  White  Star  liner  between 
New  York  and  Liverpool,  was  on  fire  while  at  sea,  and  by  the  use 
of  tarpaulins  and  injections  of  steam  the  fire  was  controlled  until 
the  Mersey  was  reached.  A  wooden  vessel  would  probably  have 
ended  her  existence  in  the  Atlantic. 


FlG.  9. —  TRANSVERSE  STRESS 

8.  As  a  corollary  to  the  above  might  be  mentioned  the  more 
favorable  marine  insurance  rates  which  may  be  obtained  both 
by  the  owner  of  the  metal  vessel  and  the  shipper  of  cargo  therein, 
by  reason  of  its  superior  seaworthiness  and  resistance  to  fire. 

As  against  these  manifest  advantages,  the  wooden  vessel  could 
only  offer  the  original  ease  with  which  its  material  could  be 
obtained  and  worked  and  a  lower  cost  of  construction,  factors 
which  were  entirely  insufficient  to  offset  the  weighty  arguments 
in  favor  of  the  stronger  material.  As  a  result,  the  metal  vessel 
became  the  common  type  of  merchant  carrier.  No  effort  will  be 
made  here  to  trace  the  history  of  the  early  metal  vessels,  which 
are  fully  described  in  many  excellent  historical  works,  and  we  will 
proceed  to  an  examination  of  the  characteristics  which  gave  steel 
preeminence  as  a  material.2 

2  See  reference?  at  the  close  of  this  chapter, 


MATERIALS  OF  CONSTRUCTION  25 

ADVANTAGES  OF  STEEL 

Iron  was  subsequently  superseded  by  steel,  which  was  first 
used  by  the  French  in  1873.  The  advantages  of  the  latter  ma- 
terial are: 

1.  An  ultimate  tensile  strength  (measure  of  stretching  force) 
from  25  to  30  per  cent  greater  than  that  of  the  best  iron  ship- 
plates. 

2.  Ductile  (capable  of  being  elongated)  and  malleable. 

3.  Homogeneous  in  substance  and  uniform  in  quality. 

4.  The  strength  is  the  same  in  all  directions,  whereas  iron  plates 
frequently  showed   15  per  cent  greater  strength  tested   length- 
wise than  breadthwise. 

5.  The  ratio  of  the  elastic  limit  (point  where  elasticity  ceases) 
to  the  ultimate  breaking  strain  is  greater  than  in  the  case  of  iron ; 
therefore,  the  -working  loads,  borne  by  the  steel  exceed  those  of 
the  iron. 

6.  In  the  earlier  vessels  classed  at  Lloyd's  there  was  a  saving  of 
from  13  to  15  per  cent  in  weight  by  the  use  of  steel,  with  increased 
cargo  and  fuel  space  thereby. 

7.  Although  the  cost  was  originally  greater,  the  increased  cost 
was  compensated  for  by  the  augmented  capacity.     As  far  back  as 
1 88 1  one  writer  worked  out  the  following  comparison  of  cost  and 
capacity  for  a  spar-decked  steamer  of  4000  gross  tons  carrying 
passengers  and  cargo  in  the  Eastern  trade  3  : 

Weight  of  iron  in  iron  steamer 2123  tons,  costing  £14,501 

Weight  of  steel  and  iron  in  steel 
steamer  1847  tons»  costing  £18,075 

Difference  —  increased  dead-weight  ca- 
pacity of  steel  steamer 275  tons,  costing  £  3,574 

The  figures  showed  that  the  extra  275  tons  dead-weight  capacity 
would  compensate  for  the  extra  cost  in  a  little  more  than  two 
years.  Later  steel  vessels  could  be  built  for  even  less  than  iron 
would  cost. 

As  a  result  of  the  advantages  described  metal  vessels  tended 
to  displace  wood  ships.  In  1860,  30  per  cent  of  the  British  ton- 
nage consisted  of  iron  vessels,  and  by  1919,  99  per  cent  was  com- 

3  W.  Denny,  Transactions  of  the  Iron  and  Steel  Institute,  Great  Britain, 
quoted  in  Holmes,  Ancient  and  Modern  Ships,  p.  44. 


26  MERCHANT  VESSELS 

posed  of  iron  and  steel.  In  the  United  States  iron  was  little 
used  before  1870,  and  before  the  World  War  35  per  cent  of  the 
tonnage  was  wooden  vessels,  although  this  is  partly  due  to  the 
coasting  trade.  The  table  at  the  close  of  this  chapter  is  illustra- 
tive of  present  conditions  in  the  American  merchant  marine. 

THE  COMPOSITE  VESSEL 

The  composite  vessel  is  really  a  metal  vessel  in  every  par- 
ticular except  the  shell,  which  is  of  wood.  While  the  prejudice 
against  iron  existed  in  1851,  it  was  nevertheless  admitted  that 
there  would  be  a  considerable  gain  in  lightness  and  space  by 
substituting  iron  frames  ands  beams  for  the  heavy  wooden  ones 
and  in  that  year  the  Tubal  Cain,  787  tons,  was  built  at  Liverpool 
in  this  style.  Between  1860  and  1870,  with  the  Suez  Canal  un- 
opened and  steamers  unprofitable  on  the  long  voyage  in  the  China 
tea  trade,  the  clean  bottom  obtained  with  a  copper  sheathing  over 
wooden  planking  was  so  important  to  a  quick  run  home  that  a 
number  of  vessels  were  so  constructed.  They  were  iron-framed, 
planked  with  teakwood  from  5  to  6  inches  thick  and  fastened 
with  Muntz-metal  bolts.  Teakwood  was  used  because  its 
natural  oil  is  a  preservative  and  it  is  the  only  wood  which  can 
be  brought  into  contact  with  iron  without  injury  to  the  iron  or 
itself.  A  copper  sheathing  completed  the  vessel  and  gave  perfect 
immunity  from  a  foul  bottom.  But  with  the  opening  of  the  canal, 
steamers  took  over  the  tea  trade,  and  although  the  composite  ves- 
sels built  gave  good  service,  the  advantages  gained  were  an  in- 
sufficient offset  to  their  great  costliness.  The  system  became 
practically  obsolete  as  regards  merchant  vessels,  and  is  used  only 
for  yachts. 

Iron  and  steel  vessels  are  sometimes  protected  below  the  water 
line  by  having  the  iron  or  steel  plating  of  the  bottom  sheathed 
with  wood  and  the  wood  covered  with  copper  sheets  secured  by 
copper  nails.  The  copper  must  be  carefully  insulated  from  the 
steel  hull  to  avoid  galvanic  action  induced  by  sea  water.  Zinc 
has  also  been  used  on  wooden  vessels,  but,  although  it  gives  pro- 
tection from  worms,  it  has  no  anti fouling  qualities.  At  one  time 
pure  copper  was  used  but  yellow  metal  has  been  substituted, 
for  with  powerful  resisting  qualities  it  is  cheaper  and  lasts 
longer. 


MATERIALS  OF  CONSTRUCTION  27 

CONCRETE  VESSELS 

Concrete  was  used  for  some  years  as  a  material  for  the  con- 
struction of  small  crafts,  barges,  etc.,  but  the  shipbuilding  diffi- 
culties of  the  World  War  suggested  the  possibility  of  applying 
this  material  to  larger  vessels.  The  demand  for  steel  could 
not  be  equaled  by  the  production  of  the  steel  mills,  there  was 
insufficient  seasoned  lumber  for  wooden  vessels,  and  shipbuild- 
ing labor  was  utterly  inadequate  to  accomplish  the  gigantic 
program  mapped  out.  After  investigation  by  the  Bureau  of 
Standards  and  the  Shipping  Board,  a  department  of  Concrete 
Ship  Construction  was  created  in  the  Shipping  Board  in  Decem- 
ber, 1917,  and  work  begun  on  the  development  of  standard 
designs  for  concrete  cargo  carriers.  Contracts  were  placed  with 
various  yards  and  the  program  at  the  close  of  1918  called  for 
the  production  of  38  tankers  and  cargo  vessels  of  7500  tons 
dead  weight,  3  cargo  ships  of  3500  tons  dead  weight  and  I 
cargo  ship  of  3000  tons  dead  weight.  Barges  are  also  being 
constructed  for  harbor  and  inland  service. 

In  the  ferro-concrete  vessel,  the  framework  is  of  steel,  and 
similar  in  character  to  the  steel  vessel,  but  the  covering  is  com- 
posed of  a  concrete  composition  of  the  highest  possible  elasticity 
and  least  possible  weight.  The  process  is  either  to  cast  the  con- 
crete in  adjustable  molds  or  to  add  steel  rods  and  wire  lath  to  the 
steel  framework  for  strength  and  cohesion  and  plaster  on  the  con- 
crete mixture.  The  latter  method  is  probably  superior.  In  Nor- 
way small  vessels  are  built  by  placing  the  concrete  over  an  in- 
verted wooden  hull  and  launching  the  vessel  bottom  up. 

The  obstacles  to  the  development  of  the  concrete  vessel  were : 

1.  The  great  weight  and  volume  of  material  necessary  to  attain 
the  required  strength.     This  was  partially  met  by  the  production 
of  a  concrete  mixture  by  government  engineers,   which  would 
not  only  float  but  was  one-fifth  lighter  than  wood.     It  possessed 
nearly  twice  the  strength  of  ordinary  concrete  mixtures.     The  fol- 
lowing table  prepared  in  England  shows  the  excess  weight  of  con- 
crete  as   compared   with    steel,   and   indicates   that   this   excess 
relatively  declines  with  the  size  of  the  vessel. 

2.  Liability  to  crack  under  stress,  the  seriousness  of  which  is 
disputed,  some  claiming  for  certain  concrete  mixtures  almost  the 
elasticity  of  steel.     Numerous  concrete  vessels  have  been  con- 


28 


MERCHANT  VESSELS 


Cargo 
capacity 
dead  weight 

Weight 
of  steel 
hull 

Weight  of 
hull  of 
reinforced 
concrete 

Excess 
weight  of 
concrete 
hull 

Excess  dis- 
placement of 
concrete 
hull 

Long  tons         Long  tons        Long  tons  Per  cent  Per  cent 


500 

250 

475 

90 

30 

1,000 

550 

950 

75 

26 

2,000 

1,050 

1,650 

57 

20 

3,000 

1,500 

2,200 

46/2 

15/2 

5,000 

2,200 

2,800 

27/2 

8/, 

structed  in  Norway.  The  illustration  is  cited  of  a  concern  which 
has  built  a  successful  seagoing  concrete  vessel  of  200  dead-weight 
tons,  a  lightship  of  the  same  material  for  the  Norwegian  Gov- 
ernment, and  a  4000  ton  ore-carrying  ship. 

3.  Concrete  is  porous  and  subject  to  deterioration  by  salt  water. 
To  offset  this,  Shipping  Board  engineers  have  devised  a  protec- 
tive coating. 

4.  As  a  cargo  carrier  the  concrete  ship  is  about  8  per  cent  more 
efficient  than  a  wooden  ship  and  about  5  per  cent  less  efficient 
than  a   steel  vessel. 

The  counterbalancing  advantages  are: 

1.  Speed  of  production,  it  being  estimated  that  after  the  experi- 
mental stage  is  passed  the  concrete  vessel  will  consume  only  one- 
half  to  one-third  the  time,  of  steel  construction. 

2.  Cheapness.     One  writer  cites  expert  estimates  of  $60,000 
worth  of  reenforced  concrete  for  a  hull  of  a  5OOO-ton  cargo  ship, 
as  compared  with  $300,000  for  a  steel  freighter  of  the  same  size. 
The  report  of  the  United  States  Shipping  Board  estimates  the 
cost  of  a  concrete  vessel  as  $70  per  dead-weight  ton  for  the  hull 
and  $150  per  ton,  complete.     A  joint  committee  of  the  American 
Concrete  Institute  and  the  Portland  Cement  Association  reported 
in  1918  a  design  for  a  concrete  vessel  of  2000  tons  capacity  on 
which  the  cost  per  dead-weight  ton  was  estimated  at  $63.     For 
steel  construction  of  similar  capacity  the  estimates  ranged  from 
$90  to  $120,  and  for  wood  construction  from  $70  to  $100. 

3.  Nonshipbuilding  labor  may  be  employed  in  its  production, 
a  factor  of  particular  importance  in  time  of  labor  scarcity.     Con- 
struction companies  claim  that  the  labor  employed  is  largely  un- 
skilled, that  house  carpenters  may  be  used  and  ship  carpenters 


MATERIALS  OF  CONSTRUCTION  29 

almost  eliminated,  and  that  the  steel  is  fabricated  and  placed 
by  a  comparatively  small  group  of  men  skilled  in  reenforcing 
steel,  assisted  by  a  large  proportion  of  common  laborers  easily 
trained  for  the  purpose. 

4.  Readily  molded  to  form. 

5.  Easily  repaired. 

6.  Vibration  reduced,  as  evidenced  by  the  experience  with  the 
Faith,  a  5ooo-ton  vessel  launched  at  San  Francisco. 

It  is  evident  that  in  a  period  such  as  we  have  just  experienced 
the  concrete  vessel  appears  of  considerable  promise.  Where  pro- 
duction at  any  cost  is  the  prime  essential  many  shortcomings  in 
service  and  durability  may  be  overlooked,  but  the  future  of  the 
concrete  vessel  is  still  doubtful.  The  latest  work  on  shipbuild- 
ing states :  "  At  the  present  concrete  ships  must  still  be  consid- 
ered as  in  an  experimental  stage,  and  until  they  have  been  built 
in  sufficient  numbers  and  operated  satisfactorily  for  continuous 
and  extended  periods  of  time  to  demonstrate  their  practicability, 
the  advisability  of  laying  down  large  numbers  of  such  vessels  is 
open  to  some  question/'  * 

PRESENT  USES  OF  WOODEN  VESSELS 

The  wooden  vessel,  though  usually  inferior  to  the  steel  carrier, 
may  at  certain  times  assume  more  than  ordinary  importance. 
Thus  we  have  seen  that  wooden  sailing  vessels  experienced  a 
temporary  popularity  during  the  period  of  high  steel  prices  in 
1899  and  1900.  During  the  World  War  tonnage  of  any  kind 
was  eagerly  desired  and  since  steel  was  unobtainable  in  sufficient 
quantities  wooden  ships  became  the  next  best  thing. 

The  following  table  shows  the  number  of  vessels  built  and  offi- 
cially numbered  in  the  United  States  since  July,  1916,  including 
vessels  built  for  foreign  owners. 

But  this  was  an  unusual  state  of  affairs.  Freight  rates  were 
high,  tonnage  was  insufficient,  and  vessels  long  considered  to  be 
obsolete  and  unseaworthy  were  resurrected  from  their  resting 
places  and  made  to  do  duty  in  a  time  of  necessity.  The  wooden 
ship  under  ordinary  conditions  will  never  be  a  serious  competitor 
as  a  cargo  carrier.  In  the  coasting  trade  where  sailing  vessels  are 

used,  in  barges,  in  tugs  where  carrying  capacity  is  not  a  factor  of 

.    .  \ 

*A,  W.  Carmichael,  Practical  Ship  Production,  New  York,  1919. 


MERCHANT  VESSELS 


Year  ending 
June  30,  1917 


Year  ending 
June  30,  1918 


Number 

Gross  tons 

Number 

Gross  tons 

Seagoing 
Steel  

114 

468,  502 

252 

I  Oil  076 

Wood            

80 

T7T   AAf) 

-«•;)•*• 
158 

21  S  7l6 

Total   

104 

500  051 

JO'J 
4IO 

**3»/  1W 

I  247  6Q2 

Non-seagoing    

I.7C2 

212  708 

I  QQO 

187  101 

Total   . 

1.546 

812.650 

2.400 

1.  410.7Q1 

importance  and  under  circumstances  where  low  investment  is  a 
dominant  factor,  however,  wood  will  continue  to  be  an  important 
construction  material.  Even  in  the  wooden  vessel,  of  course, 
iron  and  steel  have  come  to  be  extensively  used  for  reenforce- 
ment. 

The  following  diagram  shows  the  classification  of  the  world's 


MATERIALS  OF  CONSTRUCTION  31 

merchant  marine  according  to  material  of  construction  from  1890 
to  1919: 

CONSTRUCTION  MATERIAL 
WORLD'S  MERCHANT  MARINE  * 


Wood 


Iron 


Steel 


1890 

7,053,885 

10,517,513 

4,435,208 

1895 

5,534,677 

9,211,561 

10,223,101 

1900 

4,009,622 

7,398,102 

17,508,704 

1905 

3,394,850 

6,044,824 

26,445,998 

1910 

2,544,858 

4,548,599 

34,728,700 

1911 

2,409,331 

4,233,858 

36,116,427 

1912 

2,270,558 

3,981,056 

38,263,659 

•  1913 

2,113,276 

3.721,285 

41,005,887 

1914 

1,983,458 

3,529,097 

43,465,210 

1915 

1,920,264 

3,353,146 

43,912,311 

1916 

1,856,176 

3,154,091 

43,596,761 

1919 

3,513,579 

2,294,410 

45,111,284 

Comm.   Nav.  Report,   1917,  P-  66. 


REFERENCES 

1.  O'DONNELL,  E.  E.:     The  Merchant  Marine  Manual.     Boston,  1918. 

Pp.  74-85.     (On  the  method  of  construction,  principal  parts, 
and  nomenclature  of  a  wooden  ship.) 

2.  WALTON,  THOMAS:     Know  Your  Own  Ship.     Griffin  &  Co.,  Ltd., 

London,   1917.     Chaps.  Ill  and  IV.     (On  buoyancy  of  metal 
vessels  and  vessel  stresses  and  strains.) 

3.  SPRINGER,    J.    F. :     "  Concrete    Boats    a    Transportation    Asset." 

American  Industries,  July,   1918,  pp.   15-17.     (Arguments  in 
favor  of  the  concrete  vessel.) 

4.  KELLY,   R.   W.,   and   ALLEN,   F.   J.:     The  Shipbuilding  Industry. 

Houghton  Mifflin  Co.,  Boston,  1918.     Pp.  74-79.     (On  the  re- 
cent construction  of  concrete  vessels  by  the  Shipping  Board.) 

5.  PORTLAND  CEMENT  ASSOCIATION  :     Concrete  Ships.     Chicago,  1917. 

(Arguments  in  favor  of  the  concrete  vessel.) 

6.  HOLMES:     Ancient  and  Modern  Ships.     Wyman  &  Sons,  London, 

1906.     (Development  of  iron  and  steel  vessels.) 

7.  CHATTERTON,  E.  K. :    Steamships  and  Their  Story.    Cassell  &  Co. 

London,  1910. 


CHAPTER  III 
STRUCTURAL  FEATURES  OF  STEEL  VESSELS 

To  describe  the  structure  of  a  building  one  would  naturally  de- 
scribe the  shape,  position  and  methods  of  connecting  the  more 
important  structural  members.  This  would  give  a  good  concep- 
tion of  buildings  in  general,  but  however  excellent  the  impres- 
sion conveyed,  it  would  not  create  a  picture  of  any  particular 
building.  So  in  shipbuilding  no  general  description  will  convey 
a  picture  of  a  particular  vessel,  for  by  variations  in  methods  of 
construction  and  the  introduction  of  individual  features  a  vessel 
may  acquire  a  distinctive  personality.  But  the  principal  parts 
of  every  vessel  are  designed  to  serve  in  general  the  same  pur- 
poses, regardless  of  its  type  or  the  material  from  which  con- 
structed. This  chapter  will  serve  to  indicate  these  purposes,  to 
form  a  basis  for  the  discussion  of  vessel  types  partly  dependent 
on  structural  features,  and  to  make  the  reader  acquainted  with 
the  nomenclature  of  the  modern  steel  merchant  vessel.  In  this 
a  recollection  of  the  preceding  description  of  the  structure  of  the 
wooden  vessel  will  be  useful. 

The  hull  of  a  vessel  consists  of  two  parts,  the  shell,  skin  or  en- 
veloping plating,  which  in  the  wooden  ship  was  planking  made 
water-tight  by  calking,  and  the  frame,  which  in  a  general  sense 
includes  all  the  principal  members  of  the  ship  except  the  shell. 
The  framing  may  be  transverse,  longitudinal,  or  a  combination 
of  both,  which  latter  is  frequently  used.  All  frames,  in  fact,  have 
longitudinal  and  transverse  members,  but  it  is  possible  to  give 
greater  emphasis  to  either  group  and  the  emphasis  given  tends 
to  fix  the  name.  Thus  the  Isherwood  system  of  construction 
is  designated  as  longitudinal  framing,  not  because  transverse 
members  are  lacking,  but  because  there  is  continuity  of  the  main 
framing  which  runs  fore-and-aft  and  the  auxiliary  transverse 
framing  is  spaced  wider  than  in  the  sc -called  transverse  system. 

We  shall  discuss  first  the  transverse  members,  with  which  we 
have  become  familiar  through  the  consideration  of  the  wooden 

32 


STRUCTURAL  FEATURES  OF  STEEL  VESSELS         33 

ship.  Transverse  framing  was  emphasized  in  the  wooden  vessel 
and  when  iron  replaced  wood  it  was  natural  to  continue  the 
methods  of  the  past  and  merely  substitute  the  new  material.  The 
fundamental  portion  of  the  structure,  as  we  have  seen,  is  the 
keel,  which  is  a  longitudinal  member  running  fore-and-aft,  but  is 
so  basic  that  it  must  be  considered  here.  In  the  wooden  ship 


FlG.    II. —  KEELS 

the  keel  was  a  strong  and  heavy  timber  with  a  rectangular  cross- 
section,  and  this  was  naturally  replaced  at  first  by  a  bar  of  heavy 
wrought  iron  of  similar  cross  section,  which  is  now  called  a  bar 
keel  (see  Figure  n).  The  lower  outside  shell  plating  which  is 
of  steel,  is  bent  so  as  to  fit  tightly  to  the  sides  of  the  keel  and 
fastened  with  rivets  extending  through  the  keel.  Although  it  has 
the  advantage  of  strength  and  stiffness,  this  type  increases  the 
draft  of  the  vessel  without  any  corresponding  addition  to  the 


34 


MERCHANT  VESSELS 


carrying  capacity  and,  therefore,  the  tendency  has  been  to  replace 
it  with  the  flat  plate  keel  (see  Figure  n).  This  is  a  long  course 
of  plating  dished  on  each  side,  connected  to  the  lower  plates  of  the 
shell  plating  by  a  lap  joint.  On  the  flat  plate  keel  rests  a  center 
•vertical  keel  or  center  keelson  (see  Figure  n),  for  it  partakes  of 
the  nature  of  both,  being  fastened  to  the  flat  keel  by  angle  bars. 
The  transverse  frames  in  the  steel  ship  consist  of  steel  bars  in- 
stead of  timbers.  In  very  small  vessels  the  cross  section  of  these 


FlG.    12.— TRANSVERSE  FRAMES 

bars  is  the  shape  of  a  right  angle  (see  Figures  12  and  13),  but  in 
larger  vessels  this  is  reenforced  by  a  reverse  frame  of  the  same 
shape  laid  against  it  (see  Figure  12),  or  other  shapes  such  as  the 
channel,  Z-bar  or  bulbangle  (see  Figure.  12)  are  substituted.  The 
frames  (see  Figures  13  and  14)  are  attached  to  the  flat  and  vertical 
keel  at  intervals  of  from  20  to  30  inches.  The  frames  and  reverse 
frames  (see  Figure  14)  are  joined  together  as  they  run  down  from 
the  deck  until  the  side  of  the  vessel  curves  into  the  bottom,  where 
the  frame  continues  on  to  the  flat  plate  keel  to  serve  as  a  founda- 
tion for  the  outer  shell  while  the  reverse  frame  separates  from  it 
by  a  gradually  widening  space  and  finally  is  attached  to  the  upper 
portion  of  the  center  vertical  keel.  Thus  there  is  a  space  between 
the  outer  and  inner  bottom,  the  frame  serving  as  a  foundation 


STRUCTURAL  FEATURES  OF  STEEL  VESSELS         35 


for  the  former  and  the  reverse  frame  for  the  latter.     The  frames 
give  shape  to  the  vessel,   support  the   shellplating  against  the 


FlG.    13. —  FRAME  AND   SHELL  PLATING 

water  pressure,  serve  as  a  basis  for  a  double  bottom,  transmit 
vertical  forces  carried  by  the  decks  to  the  bottom  of  the  ship,  and 
encounter  the  stresses  of  "  rolling." 


F  W  P/af « 


FlG.   I.-r- FRAMEvS  AND  FLOOR  PLATE 


MERCHANT  VESSELS 


For  purposes  of  strengthening  the  bottom  of  the  ship,  plates 
called  floor  plates  are  fitted  between  the  frame  and  the  reverse 
frame  and  thus  the  construction  of  the  bottom  comes  to  resemble 
the  construction  of  a  floor  in  a  house  (see  Figures  14  and  17). 
The  floor  plates  are  attached  to  the  center  vertical  keel  by  short 
pieces  of  angle  bar,  and  in  order  to  reduce  weight,  lightening 
holes  are  cut  in  the  plates  (see  Figure  14).  The  floor  plate  is 
carried  around  the  turn  of  the  bilge  as  it  strengthens  what 
would  otherwise  be  a  weak  spot,  especially  in  a  square-bilged 


Shell  Plating  /* 


FlG.    15. —  KEELSON   AND   STRINGERS 

ship,  because  "  working "  is  more  likely  here  when  the  vessel 
is  exposed  to  the  action  of  the  waves. 

The  beams  (see  Figures  15  and  16)  are  steel  bars,  channel- 
shaped  or  bulb  angles,  connecting  the  uppermost  extremities  of  the 
frames  (in  a  single-decked  ship)  and  connecting  the  frames  at 
other  lower  points  in  a  vessel  with  more  than  one  deck.  If  the 
frames  be  considered  as  the  walls,  then  the  beams  perform  the 
same  functions  as  the  beams  of  a  house.  They  prevent  the  frames 
from  spreading  due  to  the  weight  of  cargo,  or  from  closing  like 
an  umbrella  due  to  pressure  of  water,  and  they  serve  as  a  founda- 
tion for  the  decks.  It  is  necessary  that  the  connections  of  parts 
of  a  vessel  should  be  very  efficient,  and  the  beams  are  connected 


STRUCTURAL  FEATURES  OF  STEEL  VESSELS        37 


to  the  -frames  by  beam  knees  or  brackets  (see  Figure  14). 
Where  a  hatch  opening  is  necessary  for  loading  and  unloading, 
the  beams  do  not  extend  across  the  vessel  from  frame  to  frame, 
but  are  only  "  half-beams  "  supported  by  cartings  (see  Figure  16). 
The  beams  in  a  large  vessel  are  comparatively  long  pieces -of 
steel  and  the  longer  a  bar  the  less  rigidity  it  possesses.  There 
are  inserted  under  the  center  of  the  beams,  therefore,  and  rest- 
ing on  the  center  keelson,  pillars  or  stanchions.  This  is  equivalent 
to  shortening  the  beam  one-half  and  consequently  adding  to  its 
strength.  In  addition,  by  tying  together  several  beams,  it  tends 


Of. 


Clrli* 


FlG.    l6. —  BEAMS   AND  CARLINGS 

to  cause  the  entire  combination  of  parts  to  act  as  one  piece ;  other- 
wise any  great  force  exerted  on  the  side  of  thelhip  would  cause 
the  beam  to  bend  upward  at  the  center.  Since  it  is  advisable  in 
many  cases  to  keep  the  hold  or  lower  part  of  the  vessel  as  clear  as 
possible  for  cargo,  the  elimination  of  hold  pillars  and  hold  beams 
is  aimed  at  and  secured  by  equivalent  reinforcements  of  another 
nature,  described  later. 

Bulkheads  are  partitions.  They  may  be  either  longitudinal  or 
transverse,  but  the  former  are  little  used  on  merchant  ships  due 
to  the  necessity  of  keeping  the  hold  space  sufficiently  broad. 
Transverse  bulkheads  naturally  produce  transverse  strength  and 
give  support  to  decks.  In  addition,  however,  they  subdivide  the 
ship  lengthwise  into  a  number  of  holds  or  compartments  and 
thereby  limit  the  flooding  produced  by  a  puncture  of  the  shell 
plating.  They  form,  in  other  words,  a  number  of  water-tight 
compartments  so  that  leakage  is  localized  and  safety  considerably 
increased  (Figure  18). 

A  common  feature  of  modern  vessels  is  the  double  bottom  (see 


38  MERCHANT  VESSELS 

Figure  17).  This  is  formed  by  plating  over  the  tops  of  the  floor 
plates  curving  down  to  the  outer  shell  plating  at  the  sides.  Thus 
there  is  formed  an  outer  and  an  inner  bottom.  This  feature 
might  be  continued  up  the  sides  so  as  to  give  the  vessel  a  complete 
double  shell  under  water,  as  in  the  large  passenger  liners,  but 
ordinary  cargo  vessels  have  it  only  to  the  bilge. 

Turning  attention  now  to  the  longitudinal  members,  they  all  may 
be  classified  according  to  location  into  two  groups,  those  between 
bilge  and  keel,  or  keelsons,  and  those  on  the  sides  above  the  bilge, 


FlG.    17. —  FLOOR  PLATES   AND  QOUBLE  BOTTOM 

or  stringers  (see  Figure  15).  The  most  important  keelson  is  the 
center  keelson  (see  Figure  n)  which  is  above  the  keel  and  runs 
the  length  of  the  vessel.  On  either  side  of  the  center  keelson  and 
about  midway  between  it  and  the  bilge  are  the  side  keelsons  (see 
Figure  15),  which  prevent  the  floor  plates  from  tilting.  These 
are  termed  intercostal  girders  because  they  are  composed  of  plates 
fitted  intercostally  between  the  floors  in  a  continuous  line  fore- 
and-aft  and  attached  to  them  by  angles.  The  next  keelson  is  on 
the  bilge  and  is  termed  the  bilge  keelson  (not  shown  in  Figure 
15).  The  number  of  keelsons  will  vary  with  the  size  and  type  of 
ship.  Working  up  the  side  of  vessel,  just  above  the  bilge  is  the 
bilge  stringer  (see  Figure  15),  and  then  the  side  stringer  (see 
Figure  15). 

It  has  been  stated  that  the  construction  of  the  vessel  may  be 
varied  to  meet  the  purposes  for  which  intended.  The  classifica- 
tion societies  provide  rules  for  the  construction  of  vessels  in 
order  to  meet  their  approval,  but  alternatives  are  provided  for 


STRUCTURAL  FEATURES  OF  STEEL  VESSELS         39 

attaining  the  required  structural  strength.  The  alternatives  prin- 
cipally are  (i)  a  vessel  constructed  with  hold  beams  such  as 
has  been  described,  (2)  web  frames  provided  in  lieu  of  hold 
beams,  that  is,  the  floor  plates  continued  up  the  side  of  the  vessel, 
(3)  deep  framing,  composed  of  two  angles  fitted  together  so  as 
to  form  an  extra  heavy  frame.  Hold  pillars  may  also  be  dis- 
pensed with  in  some  cases  where  an  unobstructed  hold  is  re- 
quired. This  is  practically  a  continuation  of  the  floor  plates  or 
partial  bulkheads. 

Another  system  of  framing  of  present-day  importance  is  the 


Reproduced  by  permission  from  J.   W.  Isherwood 
FlG.    l8. —  LONGITUDINAL   SYSTEM 

Isherwood  system,  in  which  emphasis  is  placed  on  the  longitudinal 
members  of  the  hull.  The  main  frames  run  fore-and-aft,  and 
the  transverse  frames  are  at  greater  intervals  than  usual.  The 
outstanding  feature  is  the  continuity  of  the  longitudinal  members, 
which  are  multiplied  in  number.  The  method  is  exceedingly 
well-adapted  to  oil  tankers,  for  which  it  is  in  almost  universal 
use.  Twelve  hundred  vessels  have  been,  or  are  being  built  by 
this  system,  aggregating  9,500,000  tons  dead-weight  capacity,  in- 
cluding 400  bulk  oil  carriers  of  3,600,000  tons  dead-weight 
capacity. 

The  transverse  frames  and  beams,  in  the  Isherwood  system, 
are  at  widely  spaced  intervals  of  about  12  feet  and  form  com- 
plete transverse  belts  around  the  vessel.  They  are  directly  riveted 


40  MERCHANT  VESSELS 

to  the  shell  plating  and  deck  of  the  vessel,  and  are  often  of 
greater  strength  than  the  transverse  frames  of  the  ordinary  form 
of  construction.  The  outer  edges  of  the  transverse  frames  are 
slotted,  however,  to  permit  the  fitting  of  continuous  longitudinal 
keelsons  or  stringers  at  the  sides,  bottom,  and  decks.  The  method 
is  not  new,  in  a  sense,  the  idea  having  been  employed  in  the 


Reproduced   by   permission   from  J.    W .   Isherwood 
FlG.    IQ. —  TRANSVERSE  SYSTEM 

construction  of  the  Great  Eastern,  a  68ofoot  transatlantic  vessel 
constructed  in  1858,  but  at  that  time  it  was  cheaper  and  easier 
to  build  on  the  old  system.  The  following  illustrations  will  con- 
vey the  idea  of  the  Isherwood  system  better  than  any  descrip- 
tion. Figure  18  is  a  photograph  of  a  vessel  under  process  of 
construction,  while  Figures  19  and  20  contrast  interior  views  of 
the  transverse  and  longitudinal  systems. 

The  advantages  claimed  for  this  type  of  construction  may  be 
summarized  as  follows : 

i.  Increased  dead  weight,  by  dispensing  with  a  number  of 
transverse  connections,  such  as  beam  knees,  bilge  brackets,  talk 
knees,  packing,  etc.,  and  reduction  of  the  longitudinal  frames  n 


STRUCTURAL  FEATURES  OF  STEEL  VESSELS        41 

accordance  with  the  water  pressure.  The  jncreased  dead  weight, 
for  example,  in  a  two-deck  cargo  vessel  500  feet  by  58  feet  4 
inches  by  35  feet  9  inches,  is  350  tons. 

2.  Increased  longitudinal  strength,  preventing  damage  to  the 
decks,  through  buckling,  for  example. 

3.  Increased  bale  and  grain  capacity,  by  reason  of  the  flat  floor 
and  the  absence  of  beam  knees  between  the  transverse  frames. 

4.  Increased  local  strength. 


Reproduced   by   permission  front  J.    W .   Isherwood 
FlG.   2O. —  LONGITUDINAL   SYSTEM 

5.  Improved  ventilation,  the  longitudinal  through  the  transverse 
frames  forming  continuous  air  passages. 

6.  Lessening  of  vibration.     The  verification  of  this  must  depend 
upon  the  experience  of  the  users.     Undue  vibration  means  in- 
creased wear  and  tear  and  cost  of  maintenance. 

7.  Ease  of  access  to  all  parts  of  the  structure,  thus  reducing 
costs  of  maintenance. 

8.  A  stronger  bottom,  particularly  valuable  in  trades  where  the 
vessel  is  compelled  to  take  the  ground  when  loading  and  discharg- 
ing or  entering  and  leaving  port. 


42  MERCHANT  VESSELS 

Aside  from  the  questions  of  strength  under  actual  usage  and  the 
relative  cost  of  repairing  damage  which  can  be  demonstrated  only 
by  experience,  the  following  disadvantages  of  the  Isherwood 
system  appear : 

1.  A  reduced  capacity  %for  cargoes  having  no  short  pieces  to 
fill  the  space  between  the  transverse  sections,  such  as  long  tim- 
bers.    In  answer  it  is  urged  that  a  broader  or  longer  vessel  could 
be  built  with  the  same  weight  of  steel  as  would  be  employed  in  a 
smaller  vessel  on  the  transverse  type.     If  the  same  dead  weight  be 
retained  in  the  larger  vessel  the  ship  can  be  of  finer  form,  resulting 
in  a  larger  ship,  equally  economically  driven  by  the  same  power 
while  having  the  same  timber  capacity  as  the  smaller  ship. 

2.  The  longitudinals  form  ledges  which  retain  a  certain  amount 
of  cargo  when  unloading,  e.  g.,  coal  and  grain  which  must  be 
swept  off.     But  when  stringers  are  used  in  the  transverse  system 
a  similar  objection  presents  itself,  with  the  additional  fact  that 
the  cleaning  is  more  difficult.     In  a  vessel  of,  say,  8000  tons  dead 
weight  the  amount  of  coal  lodging  on  longitudinals  does  not  ex- 
ceed 4  tons. 

The  remaining  feature  of  the  hull  is  the  shell  plating.  This  con- 
sists of  a  large  number  of  steel  plates  of  approximately  rectangular 
shape  arranged  in  longitudinal  courses  or  strakes.  The  plates 
range  from  ]/^  inch  to  I  inch  in  thickness,  varying  with  the  location 
and  the  size  of  vessel.  There  are  (i)  flat  plates  which  require 
little  or  no  curvature,  (2)  rolled  plates,  which  are  found  at  the 
turn  of  the  bilge,  and  (3)  flanged  or  furnaced  plates  which  re- 
quire special  shaping.  The  strake  nearest  the  keel  is  called  the 
garboard  strake,  and  the  highest  complete  strake  the  sheer  strake. 
The  plates  are  connected  by  rivets. 

TERMINOLOGY 

This  description  of  the  principal  parts  of  a  vessel  may  be  con- 
cluded by  brief  definitions  of  the  terminology  applied  to  various 
shapes,  measurements,  spaces,  and  superstructures. 

i.  Shapes. —  The  vessel  for  purposes  of  easy  propulsion  is  not 
square  at  the  bow  and  stern,  but  pointed,  and  a  smooth  curved 
line  is  formed  from  stem  to  stern,  called  the  ^vater  line.  Since 
the  shape  varies  somewhat  at  different  depths  there  is  really  a 
series  of  water  lines.  The  bottom  of  (he  vessel  is  also  rounded 


1 

1  a 


J. 


44  MERCHANT  VESSELS 

off  and  the  curved  portion  between  the  bottom  and  sides  is  the 
bilge  (see  Figure  21).  From  the  keel  to  the  bilge  the  bottom  rises 
or  slants  up  somewhat  and  this  is  termed  the  dead  rise  (see 
Figure  21).  The  width  of  the  vessel  may  be  greater  or  less 
above  the  bilge  than  at  the  bilge.  The  amount  of  the  decrease  is 
called  tumble-home  and  the  amount  of  increase  is  the  flare  (Fig- 
ure 21 ).  Camber  is  the  distance  the  center  of  the  deck  surface  is 
above  its  sides  (Figure  21).  The  decks  also  have  a  fore-and-aft 
curvature,  being  higher  at  the  bow  and  stern,  and  this  curvature 
is  called  the  sheer  (Figure  21). 

2.  Measurements. —  The  greatest  length  of  the  vessel  is  the 
length  over  all  (Figure  21),  but  there  is  also  the  length  between 
perpendiculars  (Figure  21),  which  is  the  length  usually  agreed 
upon  by  shipowner  and  builder  when  contracting  for  a  vessel  and 
that  usually  understood  when  not  otherwise  specified.     Extreme 
breadth  is  measured  over  the  outside  plating  at  the  greatest  breadth 
of  the  vessel.     M,olded  breadth  is  measured  over  the  frame  at  the 
greatest  breadth  of  the  vessel  (Figure  21).     Molded  depth  is  the 
distance  from  the  top  of  the  upper-deck  beams  at  the  side  of  the 
vessel  (Figure  21).     In  spar-decked  and  awning-decked  vessels 
it  is  measured  to  the  top  of  the  main-deck  beams  at  the  side  of 
the  vessel.     The  draft  is  the  vertical  distance  from  the  bottom  of 
the  keel  to  the  water  line  at  which  the  vessel  is  considered  as  float- 
ing (Figure  21).     Measured  forward  it  is  the  forward  draft,  and 
aft  the-  after  draft.     The  arithmetic  average  of  the  two  is  the 
mean  draft;  the  difference  between  the  two  is  the  trim  (Figure 
21 ).     Thus  a  vessel  trimming  by  the  bow  has  a  greater  forward 
than  after  draft;  trimming  by  the  stern  denotes  the  reverse. 

3.  Spaces. —  Trimming   the    ship   is    accomplished   by    water- 
tight compartments  at  the  extreme  stem  and  stern  just  above  the 
bottom,  which  are  easily  filled  with  or  emptied  of  water,  called 
the  -forward  and  after  peak  tanks.     The  greater  part  of  the  hull 
is  occupied  by  the  holds  formed  by  bulkheads  and  running  the 
width  of  the  vessel,  for  the  purpose  of  storing  cargo.     Rectangu- 
lar openings  in  the  deck,  called  hatches,  furnish  ingress  and  egress, 
covers  being  provided  for  the  openings.     Most  of  the  remainder 
of  the  hull  space  is  consumed  by  the  engine  room,  boiler  room, 
and  coal  bunkers,  or,  since  oil  has  come  into  use.  it  might  be  more 
correct  to  say,  generally,  the  propulsion  space.     Previous  illus- 
trations have  shown  the  cellular  character  of  the  double  bottom 


ii 


ii 


•jwyf/ii 
Vvtta 


.8-Kffr 


:j 


ii  I 

S«    "S 


46  MERCHANT  VESSELS 

and  these  cells,  made  water-tight,  may  serve  as  tanks  for  water 
ballast  to  trim  and  steady  the  unladen  ship  or  for  feed  water 
for  boilers. 

4.  Superstructures. —  The  principal  superstructures  are  the 
forecastle  over  the  forward  upper  portion  of  the  hull  and  some- 
times used  as  quarters  for  the  crew,  the  bridge  or  platform  amid- 
ships for  the  controlling  and  steering  apparatus,  and  the  poop  or 
after  structure,  often  containing  the  steering  gear. 

RECAPITULATION 

While  nearly  all  vessels  have  distinctive  features,  there  are 
many  important  characteristics  common  to  all  and  serving  similar 
purposes.  A  vessel  hull  consists  of  two  parts,  a  shell  and  a  frame. 
The  frame  consists  of  transverse  and  longitudinal  members,  the 
principal  transverse  members  being  the  frames,  reverse  frames, 
floor  plates,  beams,  pillars,  and  bulkheads.  The  principal  longi- 
tudinal members  are  the  keel,  keelsons,  and  stringers.  In  the 
transverse  system  of  construction  the  transverse  frames  are  em- 
phasized, and  in  the  Isherwood  system  the  longitudinal.  Both 
have  advantages  and  disadvantages,  with  the  latter  becoming  in- 
creasingly popular.  Various  terms  are  used  in  describing  the 
shape  and  measurement  of  a  vessel  and  the  principal  spaces  and 
superstructures  have  been  briefly  noted. 

REFERENCES 

1.  CARMICHAEL,  A.  W. :    Practical  Ship  Production.     McGraw-Hill 

Co.,  New  York,  1919.  Chap.  III.  (On  the  principal  parts 
and  methods  of  construction  of  steel  ships,  with  clear  explana- 
tions and  good  diagrams.) 

2.  WALTON,   THOMAS:    Steel  Ships.     Griffin  &   Co.,   London,   1918. 

Chap.  V.  (Brief  summary  of  principal  parts  and  methods  of 
construction.  More  technical  than  the  preceding.) 

3.  WALTON,  THOMAS:    Know  Your  Own  Ship.    Griffin  &  Co.,  Lon- 

don, 1917.     Pp.  66-i  18. 

4.  HOLMS,  A.  C. :     Practical  Shipbuilding.     Longmans,  Green  &  Co., 

London,  1916.  Vols.  I  and  II.  (Highly  technical,  with  sepa- 
rate chapters  devoted  to  individual  structural  features.) 

5.  CARMICHAEL,   A.  W. :    Practical   Ship   Production.     New   York, 

1919.    Pp.  31-50.     (Form,  dimensions  and  general  arrange- 
of  a.  vessel.) 


STRUCTURAL  FEATURES  OF  STEEL  VESSELS         47 


6.  ISHERWOOD,  J.  W. :     "  Modern  Shipbuilding  and  Economy  in  Ma- 

terial," paper  before  Society  of  Engineers,  London,  1918. 
Published  in  Fair  play,  London,  May  30,  1918.  (On  advantages 
of  the  Isherwood  construction.) 

7.  "  The  Isherwood  System  of   Ship   Construction,"  Fairplay,  Feb- 

ruary i,  1917.  (On  the  advantages  of  the  Isherwood  construc- 
tion. Less  technical  than  the  preceding.) 

8.  CARMICHAEL,  A.  W. :     Shipbuilding  for  Beginners.     Published  1jy 

Industrial  Service  Department,  Emergency  Fleet  Corporation. 
Washington,  1918.  (Brief  and  elementary  description  of  the 
principal  parts  and  the  building  of  a  vessel.) 

9.  WALTON,   THOMAS:    Steel  Ships.     Griffin   &   Co.,   London,    1918. 

Pp.  197-203.  (Technical  description  and  plans  of  the  Isher- 
wood system.) 


CHAPTER  IV 
TYPES  OF  MERCHANT  VESSELS 

The  object  of  the  present  chapter  is  to  give  some  conception 
of  the  various  kinds  of  merchant  vessels,  the  influences  which 
have  developed  the  existing  types,  and  the  purposes  and  advan- 
tages of  each.  This  is  obviously  a  difficult  task,  seeing  that  al- 
most every  vessel  has  its  individual  peculiarities,  some  of  which 
would  never  be  reproduced  except  under  the  specific  set  of  cir- 
cumstances in  existence  at  the  time  of  construction.  It  is  also 
difficult  to  indicate  the  advantages  of  even  important  features  of 
construction  in  view  of  the  fact  that  opinions  may  differ  as  to  their 
desirability ;  what  strongly  appeals  to  one  shipowner  might  be  in- 
stantly rejected  and  condemned  by  another ;  one  writer  considers  a 
ship  a  peculiar  product  which,  once  launched,  seems  to  become  an 
entity  in  itself,  having  an  individuality  not  perceptible  in  any  other 
product  of  human  labor.  All  that  is  possible,  therefore,  is  to  at- 
tempt some  system  of  classification  which  will  segregate  vessels 
into  groups  by  concentrating  attention  upon  some  of  their  princi- 
pal characteristics.  In  this  process  two  viewpoints  may  be 
adopted.  One  may  consider  the  vessel  with  certain  construction 
features  which  make  it  mort  adaptable  to  some  sets  of  external 
conditions  than  others,  implying  an  examination  of  its  material, 
motive  power,  form,  and  design,  capacity,  etc. ;  or  one  may  attempt 
a  survey  of  the  principal  external  factors  which  are  conducive  to 
various  forms  of  construction  and  trace  the  results  of  these  factors 
in  existing  types  of  vessels.  The  former  method,  which  has  been 
adopted  here,  works  from  the  results  to  the  causes;  the  latter 
from  the  causes  to  the  results. 

Vessels  are  constructed  for  a  variety  of  purposes  and  with  some 
of  the  resulting  ships  we  are  not  concerned.  They  may  be  clas- 
sified as  follows : 

I.     Warships 

A.  Battleships 
*B.  Cruisers 
C.  Gunboats 

48 


TYPES  OF  MERCHANT  VESSELS  49 

D.  Torpedo  craft 

E.  Mining  and  mine-destroying  vessels 

F.  Submarines 

G.  Auxiliaries 

1.  Transports 

2.  Hospital  ships 

3.  Colliers 

4.  Oil  tankers 

5.  Supply  ships 

6.  Ammunition  ships 

7.  Repair  ships 

8.  Patrol  and  Dispatch  boats 

9.  Tugs,  etc. 
II.     Merchant  vessels 

A.  Passenger  vessels 

B.  Cargo  vessels 

C.  Combination  passenger  and  cargo  ships 

D.  Tugs 

E.  Unrigged  craft 

1.  Barges 

2.  Scows 

3.  Lighters 

4.  Rafts 

III.  Whaling  and   fishing  vessels 

IV.  Pleasure  boats 

A.  Yachts 

B.  Gasoline  launches 

C.  Houseboats 

V.     Vessels  of  investigation  and  preservation 

A.  Surveying  vessels 

B.  Telegraph  vessels 

C.  Salvage  and  wrecking  vessels 

D.  Fire  boats 

E.  Dredges 

This  list  could  be  considerably  expanded,  but  the  only  section 
of  it  with  which  this  book  is  concerned  is  the  second,  dealing 
with  merchant  vessels. 

The  various  types  of  merchant  vessels  will  be  discussed  here 
with  reference  to  the  following  characteristics : 


5o  MERCHANT  VESSELS 

1.  Material  of  the  hull 

2.  Form 

3.  Speed  and  character  of  service 

4.  Strength  of  construction  and  arrangement  of  decks 

5.  Motive  power * 

MATERIAL  OF  THE  HULL 

This  phase  of  shipping  has  been  rather  fully  discussed  in  the 
preceding  chapter,  wherein  it  was  seen  that  while  steel  formed  the 
bulk  of  the  merchant  marine,  various  materials  were  and  are  used 
in  the  construction  of  vessels,  namely,  wood,  iron,  steel,  concrete. 

1.  Wood. —  This  was  the  earliest  material  in  use  and  possesses 
the  advantages  of  cheapness  and  workability,  but  the  difficulty  in 
some  countries  of  procuring  satisfactory  lumber,  the  higher  spe- 
cific gravity  of  the  wooden  vessel  as  compared  with  steel,  its  weak- 
ness under  stress,  the  limitation  on  its  size,  and  its  lower  degree 
of  safety  caused  a  gradual  diminution  in  its  use.     Wood  became, 
therefore,  principally  a  material  devoted  to  the  building  of  smaller 
vessels  which  did  not  warrant  any  considerable  investment  of 
capital,  a  product  utilized  for  coastwise  vessels  engaged  in  un- 
certain and  irregular  trade  on  the  American  coasts,  and  occasion- 
ally the  small  vessel  engaged  in  the  lighter  commerce  with  near-by 
foreign  territory.     The  lumber  trade  of  the  Pacific  Coast  offered 
a  profitable  field  for  its  employment  for  a  considerable  period, 
but  even  here  the  metal  vessel  became  a  strong  competitor.     It  is 
still    the    principal    material    for    unrigged    craft.     Occasionally 
periods  arise  when  'a  shortage  of  tonnage,  labor  conditions,  and 
the  cost  of  construction  play  so  important  a  part  as  to  make  the 
wooden  ship  profitable,  but  these  conditions  are  merely  temporary, 
and    even   in    wooden   vessels    considerable    metal    is    used    for 
strengthening. 

2.  Iron. —  Any  kind  of  metal  had  the  advantages  enumerated, 
as  compared  with  wood,  and  iron  was  naturally  first  used,  but  iron 
has  become  a  subsidiary  material  in  shipbuilding.     It  is  inferior 
to  steel  in  workability,  strength,  and  uniformity  of  quality.     Any 
former  saving  in  cost  was  more  than  compensated  for  by  the  in- 
creased capacity  of  the  steel  vessel  and  recently  even  this  differ- 
ence in  cost  has  disappeared. 

1  The  discussion  of  motive  power  is  postponed  to  Chapters  VI  and  VII. 


TYPES  OF  MERCHANT  VESSELS  51 

3.  Composite   Vessels. —  This  is  a  combination  of   a  metal 
framework  and  a  wooden  shell.     Its  principal  advantage  is  the  im- 
munity from  fouling  given  by  the  copper  sheathing,  but  this  and 
other  small  "advantages  were  an  insufficient  compensation  for  the 
greater  costliness  of  the  vessel  and  it  became  largely  obsolete  for 
merchant  vessels. 

4.  Steel. —  This  is  the  material  of  primary  importance,  at  the 
present  time  comprising  over  90  percent  of  the  world's  tonnage. 
It  offers  the  advantages   of    speedy  construction,   great  tensile 
strength,  workability,  uniform  quality,  great  elasticity,  and  con- 
siderable  saving  in   weight  and  capacity  with   reasonable   cost. 
It  is  the  basic  material  for  the  construction  of  all  the  large  and 
fast  passenger  and  freight  vessels  in  the  overseas  trade,  and  even 
the  slower  cargo  vessels  are  mainly  so  built.     Only  where  cost  of 
construction  is  a  vital  element  and  when  steel  is  scarce  can  the 
other  materials  compete  with  it.     It  is  interesting  to  observe  the 
same  progress  from  wood  to  steel  in  the  production  of  aeroplanes, 
the  all-metal  plane  being  slowly  developed. 

5.  Concrete. —  During  the  World  War,  with  the  consequent 
demand  for  speedy  production,  the  construction  of  concrete  ves- 
vels  was  undertaken.     The  end  of  the  war  made  this  largely  a 
mere  experiment,  no  experience  being  yet  available  to  demon- 
strate the  ability  of  this  mixture  to  compete  with  other  materials. 
If  it  possesses  the  necessary  qualities  for  a  shipbuilding  material 
it  offers  the  advantages  of  cheapness,  speedy  construction,  and 
employment   in   shipbuilding  of   a   new  kind  of   labor;  but  its 
deficiencies  are  its  liability  to  crack  under  stress,  the  excess  weight 
of  ordinary  mixtures,  and  its  porous  nature.     It  may  in  future 
provide  material  for  the  construction  of  barges,  scows,  etc.,  for 
which  it  has  occasionally  been  successfully  used  in  the  past,  but 
will  probably  never  in  our  time  be  an  efficient  competitor  of  the 
steel  vessel  in  the  general  cargo  or  passenger  trade. 

FORM  OF  THE  VESSEL 

The  form  of  a  vessel  is  principally  determined  by  the  shape  of 
the  hull ;  it  therefore  is  reflected  in  the  various  hull  dimensions. 
On  this  basis  a  vast  number  of  classes  might  be  set  up,  correspond- 
ing to  the  innumerable  combinations  of  various  dimensions,  but 
this  obviously  is  not  only  an  unending  task  but  conveys  no  in- 


52  MERCHANT  VESSELS 

formation.  But  it  is  just  as  plainly  evident  that  there  is  a  vast 
difference  between  the  shape  of  the  primitive  log  canoe  and  the 
form  of  a  modern  yacht.  The  principal  elements  of  form  are  the 
length,  beam,  draft,  and  freeboard,  and  the  various  forms  are 
best  described  by  giving  the  relations  between  the  vessel.'s  several 
dimensions,  such  as  the  relations  between  length  and  beam,  length 
and  depth,  etc. ;  and  the  accepted  forms  for  expressing  such  rela- 
tions, or  ratios,  are  the  following  coefficients: 

1.  Ratio  of  Length  to  Beam. —  The  ratio  of  the  length  to  the 
beam  may  be  seen  from  a  deck  plan  or  from  a  comparison  of 
longitudinal  section  with  a  transverse  section,  the  former  giving 
the  length,  and  the  latter  the  beam.     In  early  modern  vessels  the 
tendency  was  to  produce  a  low  ratio  of  length  to  beam,  that  is  to 
say,  the  beam  was  comparatively  great  as  judged  by  our  present 
standards.     Thus,   about   the   time   of   the   clipper   ship    (1850) 
British  vessels  in  the  West  Indian  trade  had  a  length  approxi- 
mately 4  times  the  breadth;   the  American   builders   increased 
the   length  to   6   and   7   times   the   breadth.     The   transatlantic 
liner  developed  from  a  vessel  with  a  ratio  of  length  to  breadth 
of  8.3  to  i  with  a  ratio  as  great  as  9.2,  as  in  the  Campania  and 
Aquitania.     A  fast  cargo  carrier  to-day  may  have  a  length  ap- 
proximately 8.5  times  its  breadth,  while  a  75oo-ton  vessel  recently 
constructed  for  the  United  States  Shipping  Board  was  about  7.2 
times  as  long  as  broad.     The  third  dimension  of  depth,  of  course, 
should  always  be  considered  in  relation  to  length  and  beam,  but, 
other  things  being  equal,  \jthe  greater  the  ratio  of  length  to  beam 
the  greater  the  speed  of  the  vessel.     Accordingly,  we  may  expect 
to  find  that  the  slow  cargo  boat,  the  sailing  vessel,  the  oil  tanker, 
and  the  coal  barge  are  comparatively  broad,  while  the  faster  cargo 
liners  and  the  speedy  mail  and  passenger  vessels  are  built  on 
"  finer  "  longitudinal  lines. 

2.  Ratio  of  Beam  and  Length  to  Draft. —  The  beam  is  a  most 
important  element  in  the  stability  of  the  vessel ;  the  greater  the 
ratio  of  beam  to  draft,  other  things  being  equal,  the  greater  the 
transverse  stability.     Where  resistance  to  "  heeling  "  is  desirable, 
therefore,  a  high  ratio  of  beam  to  draft  is  found.     An  early  trans- 
atlantic steamer  showed  a  ratio  of  1.20,  the  Lusitania  ratio  was 
1.40,  a  cargo  vessel  recently  constructed  for  the  United  States 
Shipping  Board  had  a  ratio  of  1.60,  and  a  typical  vessel  in  the 


TYPES  OF  MERCHANT  VESSELS  53 

Australian  trade  a  ratio  of  1.70.  Under  English  regulations  the 
ratio  of  length  to  depth  is  an  important  one  as  concerns  the  free- 
board and  load  line,  the  freeboard  of  a  long  vessel  being  greater 
in  proportion  to1  her  depth  than  a  small  one,  because  of  the  conse- 
quent lower  lifting  power  of  individual  waves.  The  load  line  de- 
termines the  maximum  carrying  capacity  consistent  with  safety, 
as  defined  by  the  rules,  and  the  standard  assumed  is  a  length  12 
times  the  depth. 

3.  Block  Coefficient  of  Fineness. —  This  is  one  of  the  best  in- 
dices of  form  inasmuch  as  it  takes  into  account  three  dimensions. 
Suppose  that  the  underwater  form  of  a  vessel  be  cut  out  of  a 
block  of  wood.  If  the  vessel  be  of  very  crude  form  nearly  all  of 
the  block  will  be  used  and  very  little  pared  away.  The  ratio  of 
the  volume  of  the  ship  to  the  volume  of  the  original  block  will  be 
high,  say,  .90.  On  the  other  hand,  if  the  vessel  be  of  the  more 
pleasing  form  of  a  yacht  it  will  be  necessary  to  cut  away  con- 
siderable wood  to  give  the  sharp  bow,  graceful  curves  and  over- 
hanging stern,  resulting  in  a  much  lower  ratio  of  the  volume  of 
the  finished  ship  to  the  volume  of  the  original  block,  say,  .40.  The 
diagram  on  page  54  illustrates  the  principle  of  the  block  coefficient 
of  fineness,  which  is  not  only  useful  as  an  index  of  the  form  of  the 
vessel  but  is  also  useful  as  a  factor  in  calculating  displacement 
tonnage.  It  is  possible  to  arrange  a  series  of  classes  of  vessels 
according  to  coefficients  of  fineness,  ranging  from  the  very  full  to 
the  very  fine.  In  general,  it  may  be  noted  that  the  block  co- 
efficient shows  approximately  the  following  variation : 

Slow  cargo  vessels 80 

Ordinary  cargo  vessels 75 

Sailing  vessels   70 

Mail  and  Passenger  steamers 60 

The  quality  designated  by  a  high  coefficient  is  termed  "  fullness  " ; 
by  a  low  coefficient,  "  fineness." 

In  other  respects  the  form  of  vessels  has  tended  to  become 
more  standardized.  Thus,  practically  all  cargo  vessels  and  all 
large  passenger  steamers  have  the  straight  bow,  as  distinguished 
from  the  overhanging  bow  and  extending  bowsprit  of  the  clipper 
ship  and  the  schooner  type.  The  latter  is  still  found  in  the 


54 


MERCHANT  VESSELS 


schooners  of  the  Pacific  Coast  and  some  sailing  vessels  (see  illus- 
tration on  page  5.  The  prow  of  the  faster  transatlantic 
steamers  is  sharper,  however,  than  that  of  slower  cargo  carriers 
and  the  same  is  true  of  the  stern.  "  Sheer,"  or  fore-and-aft 
curvature  of  the  deck,  supplies  lifting  power  by  the  distribution 
of  reserve  buoyancy.  A  flush-deck  vessel  without  sheer  or  its 
equivalent,  if  loaded  to  the  gunwales,  would  lack  lifting  power, 


\ 


-\ 


vv 

y 

FlG.    24. —  BLOCK   COEFFICIENTS 

and  if  nearly  submerged  would  resemble  a  submarine.  But 
although  reserve  buoyancy  is  valuable  as  resulting  in  less  water 
on  deck  and  greater  protection  to  the  crew,  if  ample  reserve  buoy- 
ancy can  be  provided  other  than  by  sheer,  the  greater  depth  at 
the  ends  provided  by  sheer  may  profitably  be  added  uniformly  the 
length  of  the  ship.  In  some  vessels  of  recent  construction  sheer 
has  been  eliminated  and  in  order  to  supply  the  reserve  buoyancy 
which  would  have  been  furnished  by  sheer  the  vessel  is  equipped 
with  a  very  high  poop  and  forecastle  extending  a  considerable 
length  at  each  end. 


TYPES  OF  MERCHANT  VESSELS  55 


SPEED  AND  CHARACTER  OF  SERVICE 

It  is  necessary  to  distinguish  between  vessels  on  the  basis  of  the 
character  of  the  service  rendered*  for  this  gives  rise  to  legal, 
structural,  and  economic  differences.  A  vessel  may  be  either 
(i)  a  common  carrier,  or  one.  which  offers  itself  as  ready  to 
transport  goods  for  any  who  may  offer  them,  the  space  being 
available  and  the  terms  mutually  satisfactory,  or  (2)  a  private 
carrier.  As  a  private  carrier  it  may  operate  in  either  of  two 
ways,  (a)  transporting  goods  for  the  same  person  who  owns  the 
vessel,  or  (b)  being  hired  out  to  another  under  contract,  in  which 
case  the  owner  of  the  vessel,  if  the  agreement  gives  the  charterer 
the  full  capacity  of  the  ship,  becomes  a  bailee  transporting  as  a 
private  carrier.  In  the  former  class  of  common  carriers  are  the 
so-called  "  line  "  vessels  and  in  the  latter  class  the  "  tramp  "  ves- 
sel and  the  industrial  carrier.  It  will  be  advisable  first  to  define 
and  indicate  the  principal  characteristics  of  the  tramp,  liner,  and 
the  industrial  carrier  and  then  proceed  to  a  comparison  of  the 
line  vessel  and  the  tramp  in  greater  detail  and  from  various  as- 
pects, indicating  the  services  rendered  by  each. 

i.  The  Tramp  Vessel. —  After  the  private  carrier  the  vessel 
engaged  in  what  is  now  called  the  tramp  service  is  the  earliest 
type  known.  When  trade  was  irregular  and  unsystematized  a 
voyage  was  more  in  the  nature  of  a  venture  than  of  a  trip.  The 
owners  expected  the  voyage  to  be  largely  governed  by  the  condi- 
tions found  to  exist  at  the  various  ports  of  call,  and  the  regions 
visited  might  be  radically  changed  by  circumstances  unforeseen  at 
the  time  of  departure.  The  owner  of  the  vessel  frequently  owned 
all  or  a  part  of  the  cargo.  An  important  individual  on  every 
ship  was  the  supercargo,  who  at  that  time  attended  to  the  ship's 
business,  delivered  cargo,  arranged  sales  of  goods  shipped  at  a 
venture,  purchased  goods  for  the  owner's  account,  or  contracted 
for  homeward  space.  The  success  of  the  voyage  depended  upon 
the  business  ability  of  the  captain  and  supercargo,  these  functions 
being  often  united.  A  voyage  therefore  was  a  most  indefinite  un- 
dertaking, as  different  from  the  regular  lines  of  to-day  as  a  peddler 
is  from  a  high-class  commercial  salesman  with  a  definite  route. 

These  vessels  were  the  precursors  of  the  modern  tramp,  a  ship 
with  no  fixed  sailing  dates,  no  constant  termini  and  no  definite 


56  MERCHANT  VESSELS 

route.  It  is  available  for  almost  any  form  of  cargo  and  varies 
its  operations  in  accordance  with  the  profits  to  be  made,  being 
usually  designed 'for  general  serviceability  and  lacking  the  spe- 
cialized features  which  will  be  seen  later  to  fit  vessels  for  particu- 
lar services.  Nevertheless,  of  recent  years  numerous  vessels 
designed  especially  for  carrying  coal,  ore,  grain,  oil,  and  frozen 
meat  have  been  built.  Such  a  vessel  may  reach  its  home  port 
only  at  intervals  of  several  years.  Thus,  a  vessel  of  this  type 
might  sail  from  New  York  with  a  cargo  of  grain  for  London, 
from  London  take  a  general  cargo  to  Australia,  thence  proceed 
with  a  cargo  of  ore  to  Europe.  It  might  there  be  chartered  to 
transport  a  cargo  of  iron  and  steel  products  to  South  America  and 
there  take  on  nitrates  for  the  United  States,  thus  finally  again 
reaching  this  country  after  being  in  nearly  all  parts  of  the  world. 
The  typical  vessel  in  this  business  is  of  about  5000  tons  gross, 
3000  tons  net,  with  a  speed  of  around  10  knots  and  a  dead-weight 
capacity  of  7800  tons.  The  tendency  is  to  increase  the  dead- 
weight capacity  of  vessels  at  present  constructed. 

2.  The  Line  Vessel. —  In  contrast  with  the  tramp,  the  line  ves- 
sel derives  its  name  from  its  operation  along  definite  routes.  It 
has  fixed  terminals  and  established  sailing  dates,  which  are  rarely 
deviated  from,  its  regularity  being  one  of  its  principal  recommen- 
dations. Thus,  instead  of  seeking  cargo,  as  the  tramp,  the  cargo 
must  seek  it  and  even  though  cargo  be  lacking  it  must  maintain 
its  schedule.  The  line  service  may  be  provided  by  vessels  char- 
tered for  the  purpose,  so  that  a  ship  may  change  its  status  from 
tramp  to  liner.  On  the  other  hand,  vessels  built  primarily  for 
line  traffic  are  generally  of  superior  character  and  speed  and  are 
consequently  seldom  utilized  as  tramps  until  unsuitable  for  the 
original  purpose.  Line  vessels  may  be  subdivided  into : 

(a)  Express  Steamers. —  These  are  floating  palaces,  designed 
primarily  for  the  accommodation  of  passengers,  with  all  modern 
luxuries  and  exceptional  speed.     As  an  illustration  the  Maurc- 
tania  may  be  cited  —  length,  787  feet;  breadth  molded,  88  feet; 
gross  tonnage,  31,550;  dead-weight  capacity,  1500  tons;  speed,  25 
knots.     These  vessels  have  been   most   fully   developed  on   the 
North  Atlantic  route,  due  to  the  overwhelming  importance  of  the 
passenger  traffic.     The  freight  capacity  is  small. 

(b)  High-Speed  Passenger  Steamers. —  These  are  slightly  in- 
ferior in  speed  but  scarcely  in  comfort  to  the  immense  express 


TYPES  OF  MERCHANT  VESSELS  57 

liners,  though  they  lack  the  ornateness  and  some  of  the  luxury  of 
the  larger  vessels.  The  Campania,  Lucania,  Celtic,  and  Cedric 
might  be  cited  as  illustrations  of  Cunard  and  White  Star  liners 
of  this  type.  They  are  around  20,000  gross  tons  with  a  speed  of 
from  1 6  to  20  knots. 

(c)  Combination' Vessels. —  These  vary  all  the  way  from  those 
built  primarily  for  passenger  accommodation  to  those  intended 
mainly  for  freight.     They  are  principally  the  outgrowth  of  con- 
ditions in  the  North  Atlantic  route.     Owing  to  the  passenger 
traffic,  a  combination  stea-mer  can  be  operated  more  economically 
and  cheaply  for  freight  than  a  freight  ship.     In  fact  the  cargo 
space  in  these  combination  vessels  is  frequently  excessive  as  com- 
pared with  the  goods  offered,  so  that  commodities  are  carried  at 
far  cheaper  rates  than  would  otherwise  be  possible.     The  George 
Washington  may  be  cited  as  an  illustration  of  this  type  of  vessel. 
She  has  a  speed  of  around  18  knots  and  a  gross  register  of  18,000 
tons.     Another  illustration  of  the  use  of  these  vessels  is  found  in 
the  trade  between  the  United  Kingdom  and  the  Far  East,  a  typi- 
cal vessel  being  550  feet  in  length  .and  of  12,000  tons  gross  reg- 
ister. 

(d)  Cargo  Liners. —  There  are  many  lines  which  are  primarily 
or  entirely  freight  lines.     The  South  American  trade  furnishes 
an  excellent  illustration,  of  this  type  of  vessel,  practically  all  the 
lines  being  freight  carriers  exclusively.     Their  vessels  are  built 
to  attain   a   moderate   speed   with   considerable   cargo   capacity. 
They  carry  tools,  scientific  instruments,  cotton  goods,  flour,  and 
hardware  to  South  America,  and  bring  in  return  coffee,  rubber, 
cocoa,  etc.     The  service  furnished  is  equivalent  in  regularity  to  the 
high-class  passenger  lines  but  at  half  the  speed. 

3.  Industrial  Carriers. —  With  the  tendency  toward  integration 
of  industry  and  the  progress  of  large  corporations  toward  owner- 
ship of  all  the  essential  factors  entering  into  the  preparation  and 
marketing  of  their  products  it  was  inevitable  that  industrial  and 
commercial  companies  should  come  to  own  and  operate  the  ves- 
sels which  carry  their  products.  In  some  cases  this  result  is  at- 
tained by  building  and  owning  fleets,  and  in  others  by  chartering 
or  hiring  vessels  from  others.  Regular  lines  are  thereby  estab- 
lished by  these  concerns  for  the  carriage  of  their  products  and  fre- 
quently in  addition  they  will  carry  commodities  for  others,  becom- 
ing common  carriers  to  this  extent.  The  designation  "  industrial 


58  MERCHANT  VESSELS 

carrier  "  is  used  here,  however,  to  designate  vessels  and  lines  which 
were  primarily  established  for  the  convenience  or  profit  of  a  spe- 
cific industrial  or  commercial  concern  in  the  carriage  of  the  com- 
modities in  which  it  deals.  The  articles  in  which  this  policy  has 
been  more  highly  developed  are  coal,  iron,  fruit,  fish,  oil,  asphalt, 
and  lumber.  We  have,  for  example,  lines  of  the  United  States 
Steel  Corporation,  operated  through  the  United  States  Steel 
Products  Company,  serving  between  New  York  and  Brazil  and 
New  York  and  Vancouver;  the  operation  of  vessels  in  the  coal 
trade  by  the  Dominion  Coal  Company,  and  by  many  eastern  rail- 
roads ;  Standard  Oil  Company  supplies  and  products  are  collected 
and  distributed  in  many  parts  of  the  world  by  more  than  60  tank 
vessels ;  the  commercial  firm  of  Grace  &  Company  operated  a  line 
to  the  west  coast  of  South  America ;  many  lumber  concerns  of  the 
Pacific  Coast  own  and  operate  fleets  of  steam  schooners  and  sail- 
ing vessels  in  the  domestic  trade  and  some  in  the  foreign  trade ; 
the  United  Fruit  Company  owns  and  operates  over  40  vessels 
aggregating  several  hundred  thousand  tons,  engaged  in  conveying 
tropical  fruits  from  Jamaica,  Guatemala,  Honduras,  Costa  Rica, 
Panama,  and  Colombia.  In  the  domestic  trade  this  policy  is  also 
apparent.  One  might  cite  the  illustration  of  the  Great  Lakes, 
where  consolidations  of  coal  and  ore  carriers,  stock  ownership  by 
industrial  concerns,  arrangement  of  chartering  facilities,  and  in- 
terrelations between  industrial  corporations  and  carriers  have 
made  the  latter  practically  an  integral  part  of  the  former.  The 
advantages  of  private  ownership  of  the  means  of  communica- 
tion have  principally  been  the  following:  (i)  The  development 
of  vessels  particularly  suited  to  the  individual  trade,  as  for  in- 
stance, the  fruit  trade.  Most  of  the  companies  first  chartered 
vessels  from  other  owners  and  after  a  period  of  development  be- 
gan to  build  vessels  specially  adapted  to  their  businesses.  (2)  The 
acquisition  of  a  service  which  exactly  met  the  needs  of  the  cor- 
poration as  regards  regularity  and  frequency.  (3)  Independence 
of  the  common-carrier  transportation  facilities,  which  evidence 
has  shown  often  exerted  considerable  influence  over  producers 
and  traders  in  certain  areas.  (4)  A  reduction  of  the  costs  of 
transportation  by  eliminating  the  carrier's  profit.  (5)  An  in- 
creased domination  of  the  particular  industry  as  far  as  water 
transportation  facilities  could  contribute  to  this  end. 

From  the  standpoint  of  the  public,  the  benefits  of  this  develop- 


TYPES  OF  MERCHANT  VESSELS  59 

ment  have  been  (i)  specialized  equipment,  resulting  in  better 
handling  and  quality  of  products;  (2)  growth  of  transportation 
facilities  in  regions  otherwise  p'oorly  served;  (3)  increased  regu- 
larity of  service ;  (4)  greater  actual  and  potential  competition  by 
American  concerns  with  foreign  producers;  (5)  possible  reduc- 
tion in  cost  of  product  by  economical  management  of  the  carrying 
trade. 

Comparison  of  Line  and  Tramp  Services. — 

(a)  Standardisation. —  From  the  character  of  the  services,  the 
products  carried,  and  the  condition  under  which  business  is  car- 
ried on,  it  has  necessarily  resulted  that  in  the  line  traffic  the  effects 
of  specialization  have  been  most  keenly  felt,  while  in  the  tramp 
traffic  generally   standardization  has  been  an  important   factor. 
In  the  line  traffic  a  carrier  serves  continuously  the  same  ports  and 
carries  approximately  the  same  kinds  of  product,  so  that  it  is 
possible  fairly  closely  to  adapt  the  type  of  the  vessel  to  the  char- 
acter of  the  trade,  resulting,  for  example,  in  the  development  of 
refrigerating  apparatus  in  the  trade  between  England  and  Aus- 
tralia and  in  the  trade  between  the  west  and  east  coasts  of  the 
United  States ;  in  the  immense  combination  liner  in  the  Atlantic 
trade ;  in  vessels  specially  adapted  to  carrying  sugar  in  the  Ameri- 
can-Hawaiian trade.     Since  the  tramp  must  accommodate  itself 
to  the  business  which  is  offered  and  must  carry  a  variety  of  prod- 
ucts,  few  owners  care  to  incorporate  features  which  might  at 
times  be  a  detriment  rather  than  a  profit.     This  results  in  a  ten- 
dency toward  a  generally  useful  vessel  and,  with  the  inducement 
to  copy  the  economical  and  successful  vessel,  in  a  tendency  to- 
ward standardization,  which  reduces  construction  costs  but  like- 
wise individuality. 

(b)  Types  of  Cargo. —  While  the  line  vessel  will  carry  cargo  of 
all  descriptions,  since  its  rates  are  usually  higher  it  will  naturally 
tend  to  transport  goods  of  relatively  high  value  as  compared  with 
their  bulk,  which  can  afford  to  pay  the  higher  rates.     The  line 
furnishes  speedier  transportation,  a  quality  which  costs,  and  con- 
sequently low-grade  goods  are  not  likely  to  seek  this  means  of 
transportation.     Grain,   cotton,    foodstuffs,   and  metal   manufac- 
tures are  frequently  carried  in  considerable  quantities,  however. 
The  tramp  vessel,  on  the  other  hand,  will  mainly  carry  goods  which 
do  not  require  speedy  delivery,  which  commercial  arrangements  do 
not  require  to  be  delivered  regularly,  which  are  susceptible  of 


6o  MERCHANT  VESSELS 

i 

loading  and  unloading  without  exceptional  facilities,  and  which 
are  comparatively  of  great  bulk  and  low  value.  Thus  we  find 
that  tramps  are  extensively  employed  in  the  grain  trade  of  the 
United  States,  Argentina,  and  India,  in  carrying  nitrate  from 
Chile,  in  transporting  lumber  on  the  Pacific  Coast,  in  bringing  ore 
from  Spain,  Cuba,  and  Chile,  in  carrying  sugar  from  Porto  Rico, 
and  occasionally  coffee  from  Brazil,  in  carrying  fibers  from  the 
Far  East,  and  coal  from  Great  Britain  and  South  Africa.  Occa- 
sionally, however,  tramps  may  be  chartered  for  the  carriage  of 
steel  products  or  machinery  by  large  corporations.  Occasionally 
also,  as  described  later,  they  are  loaded  with  small  lots  of  cargo 
belonging  to  various  owners,  but  they  commonly  carry  goods  mov- 
ing in  full  vessel  loads. 

(c)  Contracts. —  The  contract   for  the  carriage  of   goods   is 
called  *'  a  contract  of  affreightment."     The  carriage  is  performed 
in  either  of  two  ways :     ( I )  The  owner  may  operate  a  line,  state 
his  terms  and  carry  goods  for  any  who  offer  them,  in  which  case 
the  essential  document   embodying  the   agreement  between  the 
carrier  and  the  shipper  is  a  bill  of  lading.     (2)  The  owner  may 
hire  out  his  ship's  services  to  a  person  who  has  goods  of  his  own 
to  transport.     The  agreement  in  this  case  is  essentially  a  lease, 
with  many  important  special  features,  called  a  charter  party.     The 
bill  of  lading  is  therefore  usually  the  important  document  in  line 
traffic  and  the  charter  party  in  tramp  vessel  operation.     This  is 
not  the  place,  however,  for  a  discussion  of  the  provisions  and  uses 
of  these  documents.2 

(d)  Methods  of  Operations. —  The  tramp  vessel  is  frequently 
owned  by  an  individual  or  a  firm,  and  in  some  cases  is  even  divided 
into  shares  and  owned  by  a  number  of  individuals,  while  the  line 
traffic  has  practically  become  the  property  of  large  corporations, 
which  alone  can  afford  the  necessarily  large  investment  of  capital 
The  tramp  vessel  may  be  operated  in  any  of  the  following  ways : 

Carriage  of  its  owner's  goods 
Carriage  for  hire 

Leased  to  a  line  for  operation  in  line  service 
Chartered  to  a  shipper  for  carriage  of  full  cargoes 
On  a  time  charter 
On  a  voyage  charter 
Placed  on  the  berth 

2  For  such  a  discussion  see  G.   G.   Huebner,   Ocean  Steamship    Traffic 
Management,  D.  Appleton  &  Co.,  N.  Y.,  1920,  Chaps.  XI,  XII,  and  XIII. 


TYPES  OF  MERCHANT  VESSELS  61 

The  latter  method  means  that  an  agent  announces  that  he  will 
sail  the  vessel  on  a  given  voyage  "  if  sufficient  cargo  is  offered." 
If  enough  goods  are  obtained  on  provisional  contracts  the  engage- 
ment is  made  final  and  the  goods  are  loaded.  The  cargo  therefore 
consists  of  a  number  of  relatively  small  consignments  usually, 
and  the  rates  are  made  on  the  charter  basis.  Similar  goods  in 
similar  amounts  may  be  carried  for  very  different  rates  of  freight, 
the  agent  getting  what  he  can  for  the  various  shipments.  The 
line  vessel,  on  the  other  hand,  must  maintain  regular  and  sufficient 
sailings  and  fairly  stable  rates.  The  sailing  takes  place  when  an- 
nounced, whether  warranted  by  the  cargo  offered  or  not.  Offices 
and  agents  are  maintained  for  the  transaction  of  business,  while 
the  tramp  business  is  mainly  carried  on  through  ship  brokers,  who 
furnish  vessels  and  seek  cargoes  for  vessels,  receiving  a  percen- 
tage of  the  freight  for  their  services.  The  innumerable  brokers 
are  all  connected  by  the  telegraph  and  telephone  network  of 
the  world,  so  that  vessels  and  cargoes  may  proceed  from 
place  to  place  in  accordance  with  the  supply  and  demand  for 
each. 

The  organization  of  the  line  traffic  has  proceeded  even  further 
than  the  individual  line  or  individual  steamship  company.  In 
their  efforts  to  influence  service,  rates,  competition,  relations  at 
ports,  etc.,  the  lines  have  in  many  cases  entered  into  associations 
or  agreements,  designed  to  fix  common  rates,  apportion  the  traffic 
between  otherwise  competing  lines,  retain  business  of  shippers, 
maintain  regular  services,  and  promote  cooperative  issuance  of 
tariffs.3 

(e)  Types  of  Vessels  Employed. —  There  is,  of  course,  no  def- 
inite line  of  distinction  between  the  line  vessel  and  the  tramp  as 
far  as  type  is  concerned,  for  the  tramp  is  frequently  chartered  for 
line  service,  though  the  liner  rarely  becomes  a  tramp.  The  fol- 
lowing table  will  be  interesting,  however,  as  showing  the  dif- 
ferences between  the  typical  vessels  of  each  kind. 

The  following  table  shows  that  the  line  vessel  may  range  all  the 
way  from  a  5000  or  6000- ton  cargo  liner  with  a  speed  of  10  knots 
to  an  express  liner  designed  especially  for -passengers,  with  a  gross 
register  tonnage  of  60,000  and  a  speed  of  30  knots.  The  large 

3  Methods  of  operation  and  organization  of  lines  and  tramps  are  exten- 
sively described  in  G.  G.  Huebner,  Ocean  Steamship  Traffic  Management, 
D.  Appleton  &  Co.,  New  York,  1920,  Chap.  V. 


62 


MERCHANT  VESSELS 


Cargo 


Gross  tons 


LINERS 

Express  liners 
High  speed 
Combination 
Cargo 

Passengers 
Passengers  or  goods 
Passengers  and  goods 
Goods 

50,000-60,000 
20,000-30,000 
15,000-30,000 
8,000-15,000 

25-30 
20-25 

IO-2O 
10-15 

TRAMPS 

High  speed 
Low  speed 

Goods 
Goods 

2,000-15,000 
2,000-15,000 

10-13 

8-10 

INDUSTRIAL 

CARRIERS 

General  cargo 
Specialized  equip- 
ment 

Goods 
Goods  —  occasionally 
passengers 

2,000-10,000 
4,000-15,000 

8-10 
10-15 

tramp  vessel  is  375  feet  in  length,  has  a  gross  registered  tonnage  of 
about  7500  tons  and  attains  a  speed  of  from  8  to  10  knots.  The 
liner  serves  the  important  ports  of  the  world,  where  channels  and 
harbors  are  made  for  its  convenience,  while  the  tramp  must  ac- 
commodate its  draft  to  the  terminals  it  visits.  It  is  designed  to 
afford  the  largest  possible  cargo  capacity  in  proportion  to  its  in- 
ternal volume.  Thus,  a  tramp  of  only  2500  tons  gross  may  have 
a  dead-weight  cargo  capacity  of  6000  tons,  while  a  transatlantic 
palace  of  30,000  tons  may  afford  space  for  only  several  thousand 
tons  of  cargo.  The  tramp  is  designed  for  general  utility  with 
the  factor  of  economy  always  an  important  one.  It  will  there- 
fore be  built  for  carrying  capacity  rather  than  for  speed,  and  the 
construction  cost  is  usually  reduced  to  the  minimum  consistent 
with  its  purposes.  In  form  the  tramp  will  be  full,  having  a  block 
coefficient  of  around  80  per  cent,  as  compared  with  the  60  per 
cent  of  a  passenger  liner.  The  high  coefficient  is  obtained 
through  the  blunt  bow,  flat  bottom,  and  straight  sides  of  the 
tramp,  replacing  the  sharper  bow,  curved  bottom,  and  finer  under- 
water lines  of  the  liner.  Naturally  the  cargo  liner  approaches  the 
form  of  the  tramp.  It  is  difficult  to  particularize  further  on  the 
type  of  the  tramp  steamer,  owing  to  the  variety  of  cargo  carried. 
In  the  main,  goods  are  bulky,  but  they  are  not  necessarily  of  great 
density.  The  tramp  cargo  may  vary  from  wool  with  a  weight  of 
15  pounds  per  cubic  foot  to  coal  at  94  or  chalk  at  156  pounds  per 
cubic  foot.  But  in  order  to  be  of  the  greatest  earning  power  it  is 


TYPES  OF  MERCHANT  VESSELS  63 

necessary  that  the  vessel  be  fully  occupied  when  loaded  to  the 
maximum  draft.  For  cargoes  of  great  density  this  requires  a 
vessel  of  at  least  moderately  strong  construction.  In  Great  Brit- 
ain the  freeboard  is  dependent  upon  structural  conditions  and  in 
order  to  obtain  the  smallest  freeboard  and  consequent  large  load- 
ing capacity  the  strongest  construction  is  required.  In  the  trades 
where  cargoes  of  this  nature  are  the  rule,  therefore,  the  full- 
scantling-  vessel  is  employed,  while  vessels  of  lighter  construction, 
such  as  spar-decked  and  raised  quarter-decked  vessels  are  used 
for  general  cargo.  These  types  are  discussed  in  the  next  section. 
Where  relatively  little  cargo  and  many  passengers  are  carried  the 
vessel  may  be  of  very  light  construction  toward  the  upper  deck. 
Such  a  vessel  would  have  great  freeboard,  and  the  upper  deck 
would  consequently  be  more  free  from  water. 

(f)  Relative  Economy. —  In  this  connection  it  may  be  said  in 
general  that  the  tramp  obtains  economy  at  the  expense  of  speed, 
while  the  liner's  advantage  must  be  compensated  for  by  increased 
expenditures  in  many  directions.  From  nnp-q«artpr  tn  nnp-Vmlf 
the  working  expenses  of  ^  Yffi^1  rnnsigt  nf  fnpl  fpst.  and  the 
familiar  economic  "law  o.f  diminishing  returns"  is  also  apparent 
in  the  shipping  business.  Beyond  a  certain  point  the  extra  speed 
attained  is  not  proportionate  to  the  additional  fuel  required.  Thus, 
an  immense  steamer  reaching  a  speed  of  25  knots  does  so  at  the 
expense  of  twenty  times  the  coal  required  for  a  lo-knot  freighter. 
The  coal  consumed  by  a  large  transatlantic  liner  in  one  voyage 
from  New  »York  to  Liverpool  would  be  sufficient  for  ten  such 
voyages  by  a  slow  cargo  carrier.  The  liner  therefore  pays  heavily 
for  the  privilege  of  making  more  voyages  annually  and  collecting 
higher  freight  rates.  In  addition,  greater  fuel  space  and  engine 
space  must  be  provided  at  the  expense  of  productive  space,  the 
schedule  must  be  maintained  regardless  of  freight  earned,  the 
construction  cost  of  vessels  is  higher  and  the  management  expenses 
are  great,  for  advertising  is  employed  to  create  traffic,  offices 
must  be  maintained  to  handle  the  business,  and  the  staff  must  be 
sufficient  to  care  for  the  largest  volume  of  business,  though  part 
of  it  may  be  idle  in  duller  times.  Special  equipment  must  often 
be  provided  and  operated  in  specific  trades,  such  as  refrigera- 
tion facilities.  The  economies  of  the  tramp  vessel  may  be  briefly 
summarized  as  economies  of  (i)  construction,  (2)  navigation, 
and  (3)  management. 


64  MERCHANT  VESSELS 

(g)  Rates. —  Aside  from  the  fact  that  the  tramp  rates  are  in 
the  long  run  lower  than  the  line  rates,  their  outstanding  feature 
is  a  relatively  greater  fluctuation.  Thus,  charter  rates  are  prin- 
cipally dependent  upon  the  supply  of  and  demand  for  tonnage; 
the  years  1900  and  1912,  and  the  years  of  the  World  War  were 
years  of  prosperity  and  high  rates  for  the  vessel  owner,  while 
1896,  1904,  and  1908  were  comparatively  poor  years.  So  great 
is  this  fluctuation  in  rates_Jjhat  ^  middleman  in  the  form Tof  a 
speculator  has  stepped  intothe  business,  who  stands  ready  to 
make  contracts  for  steamer  space  in  advance.  The  extreme 
fluctuations  of  charter  rates  as  compared  with  line  rates  are  in 
part  due  to  the  lack  of  organization  of  the  business.  Thus  the 
charter-party  terms  may  vary  somewhat,  the  local  conditions  may 
not  be  in  accordance  with  general  conditions  due  to  a  local  excess 
or  deficit  in  vessel  tonnage  and  the  effects  are  felt  of  unrestrained 
competition,  which  is  considerably  diminished  in  the  line  traffic 
by  the  existence  of  the  associations  and  agreements  previously  re- 
ferred to.  Some  efforts  at  tramp  combination  have  been  made 
but  the  nature  of  the  business  makes  it  difficult  to  see  how  they 
can  be  permanently  successful.  There  is  some  interrelation  be- 
tween line  and  charter  rates  owing  to  the  potential  competition  of 
the  tramp  vessel,  but  investigation  has  shown  that  this  as  a  regu- 
latory factor  has  been  considerably  exaggerated.  The  present 
contrast  shows  how  distinct  the  two  classes  of  service  are  in  prac- 
tice. 

(h)  Earnings. —  A  discussion  of  shipping  profits  would  take  us 
too  far  into  the  field  of  finance.  It  is  sufficient  here  to  say  that 
profits  in  general  have  always  been  very  variable.  This  is  par- 
ticularly true  of  the  tramp  companies,  which  suffer  heavily  in 
periods  of  depression.  The  traffic  of  the  lines  is  relatively  more 
stable  and  their  financial  policy  is  better  adapted  usually  to  the 
variations  in  business,  reserve  funds  for  contingencies  being  built 
up.  Fairplay,  an  English  shipping  journal,  reproduced  a  table  of 
cargo-boat  earnings  for  ten  years,  the  average  ten-year  percent- 
age dividend  on  capital  being  4.7  per  cent.  The  annual  per- 
centage varied,  however,  from  1.9  per  cent  in  1909  to  12.6  per 
cent  in  1913.  During  the  same  period  the  dividend  record  of 
the  Hamburg-American  Line,  one  of  the  largest,  varied  from  o 
to  1 1  per  cent. 


TYPES  OF  MERCHANT  VESSELS  65 

(i)  Extent  of  Tonnage. —  It  is  estimated  that  the  tramp 
vessels  are  25  times  as  numerous  as  the  line  vessels.  But  the  latter 
naturally  make  a  better  showing  in  gross  tonnage  because  of  their 
larger  individual  size,  and  approximately  40  per  cent  of  the  total 
tonnage  is  estimated  to  be  line  tonnage  and  60  per  cent  tramp.  Of 
the  tramp  tonnage  Great  Britain  probably  owns  at  least  two-thirds. 
The  possession  of  the  tramp  tonnage  is  divided  among  possibly  40 
times  as  many  owners  as  the  line  tonnage,  nearly  all  of  which  is 
found  in  the  hands  of  about  100  large  companies. 


CHAPTER  V 

TYPES  OF  MERCHANT  VESSELS  (Continued} 
CONSTRUCTION  AND  ARRANGEMENT  OF  DECKS 

Relation  of  the  Load  Line  to  Type  of  Vessel. — It  is  advisable 
to  introduce  the  subject  of  types  of  construction  by  a  brief  ex- 
planation of  "  load  line  "  and  "  freeboard,"  with  which  it  is  closely 
connected.  The  load  line  is  the  *'  line  of  surface  of  the  water 
on  a  ship  when  loaded  to  the  maximum  allowance."  Freeboard 
is  the  "  vertical  distance  from  the  upper  water-tight  deck  to  the 
water  line  when  the  ship  is  fully  loaded,"  or  the  "  height  of  the 
upper  deck  above  water,  taken  amidships  at  the  gunwale."  It 
is  evident  that  the  weight  of  cargo  influencing  the  load  line  and 
freeboard  and  the  structural  strength  of  the  vessel  bear  some 
relation  to  each  other.  There  is  obviously  a  great  difference  be- 
tween a  steam  yacht  carrying  comparatively  little  weight  and  even 
requiring  permanent  ballast  adequately  to  immerse  it  and  a  slow 
tramp  steamer  weighted  down  with  cargo  of  great  density.  In 
the  latter  case  there  immediately  arises  the  question  of  whether 
there  are  sufficient  structural  strength  and  seaworthy  qualities. 
It  would  be  absurd  to  construct  all  vessels  of  equal  strength,  for 
if  one  is  intended  to  carry  a  cargo  of  coal  and  the  other  a  cargo 
of  wool,  either  one  would  be  too  weak  for  its  purpose  or  the 
other  excessively  strong.  The  relation  between  load  line  and  con- 
struction may  be  stated  from  two  viewpoints  with  the  same  im- 
port:  (i)  There  is  for  every  vessel  a  certain  load  line  (though 
admittedly  difficult  to  fix)  which  marks  a  limit  not  to  be  exceeded 
if  one  is  to  avoid  (a)  straining  the  structure,  or  (b)  losing  the 
necessary  weatherly  qualities.  (2)  Assuming  a  certain  required 
load  line  or  capacity,  a  vessel  is  built  with  a  certain  strength  and 
seav  orthiness.  For  the  present  purpose  weatherly  qualities  may 
be  described  as  follows : 

a.  Protection  from  sweeping  waves  by  adequate  reserve 
buoyancy,  which  is  principally  obtained  by  having  the  side  a 

66 


TYPES  OF  MERCHANT  VESSELS  67 

sufficient  distance  out  of  water,  or  freeboard.  This  is  necessary 
to  render  the  deck  safe  for  operation,  prevent  the  gear,  ventilators, 
hatch  covers,  etc.,  from  being  swept  away,  promote  the  comfort 
of  passengers,  make  bulkhead  divisions  effective,  prevent  water 
from  penetrating  below,  etc. 

b.  Wave-riding  qualities,  or  proper  distribution  of  reserve 
buoyancy,  which  is  obtained  by  sheer  or  superstructures.  The 
bow  and  stern  must  encounter  approaching  and  overtaking  waves, 
and  here  buoyancy  is  most  effective/  A  flush-deck  vessel  with- 
out sheer  or  superstructures  would  be  inferior  in  weatherly  quali- 
ties. This  reserve  buoyancy,  4<  liveliness,"  or  "  lifting  power," 
must  be  measured  relatively  by  the  ratio  of  the  volume  of  re- 
serve buoyancy  to  the  vessel's  weight  or  displacement. 

The  load  line  is  of  great  importance  in  two  ways:  from  the 
standpoint  of  safety,  which  is  apparent,  and  from  the  commercial 
standpoint.  A  vessel's  earning  power  depends  upon  its  ability  to 
carry  cargo,  and  if  the  freeboard  required  is  too  great  the  owner 
is  necessarily  discriminated  against.  Great  Britain  attempted  to 
furnish  the  necessary  safety  by  requiring  all  British  merchant 
vessels  over  80  tons  to  have  an  official  load  line  assigned  to  them 
beyond  which  they  could  not  be  loaded,  and  tried  to  maintain 
equity  by  having  such  load  lines  assigned  by  expert  calculation 
of  '*  classification  societies."  1  No  such  requirement  exists  in  the 
United  States,  for,  although  its  necessity  is  recognized,  the  load 
line  is  "  obtained  by  rules  largely  artificial  in  character,"  and 
with  many  different  types  of  vessel  engaged  in  a  variety  of  trades 

1  In  1876  it  was  enacted  in  Parliament  that  vessels  should  have  a  free- 
board mark  painted  on  the  side  (since  known  as  a  Plimsoll  mark),  but 
since  it  was  furnished  by  owners  themselves  it  was  no  guarantee  of  safety. 
It  was  frequently  arrived  at  by  a  rough  rule  which  took  no  account  of  the 
vessel's  proportions  or  form.  In  1882  Lloyd's  published  a  set  of  free- 
board tables  based  on  experience  and  consultation,  and  one  year  later  a 
Board  of  Trade  committee  investigated  the  subject  and  practically  en- 
dorsed these  tables.  In  1890  an  official  mark  was  made  compulsory  for 
all  British  vessels.  In  1906  the  freeboards  assigned  were  found  to  be 
excessive,  enabling  foreigners  safely  to  get  deeper  loading  than  British 
vessels,  and  the  tables  were  revised,  among  other  things  reducing  the  free- 
board for  vessels  with  superstructures  and  protected  deck  openings.  In 
1913  an  investigation  by  the  Board  of  Trade  resulted  in  general  approval  of 
the  existing  requirements,  with  some  modifications  to  remove  the  preferen- 
tial treatment  of  special  newer  types  of  vessels.  The  freeboard  is^  based 
principally  upon  (i)  a  standard  strength,  (2)  a  standard  ratio  of  length 
and  depth,  (3)  depth,  (4)  coefficient  of  fineness,  (5)  a  standard  sheer, 
(6)  a  standard  camber,  and  (7)  superstructures. 


il 


68  MERCHANT  VESSELS 

discrimination  between  vessels  and  between  nationalities  is  feared, 
The  latter  might  be  avoided  by  international  action.  The  British 
marks  have  accordingly  been  the  principal  standard  used  in  over- 
seas traffic. 

CLASSIFICATION  BY  STRUCTURAL  FEATURES 

In  the  following  classification  it  will  be  noticed  that  vessels  are 
primarily  segregated  into  three  groups  on  the  basis  of  structural 
features:  (i)  The  full-scantling  vessel,  (2)  the  spar-deck  vessel, 
(3)  the  awning  deck  vessel.2 

Each  group  is  separately  discussed  with  its  modifications  and 
customary  supplementary  features,  such  as  superstructures,  deck 
erections,  etc.  These  three  types  for  steel  vessels  are  men- 
tioned in  the  tables  and  rules  fixed  by  the  British  Parliament,  from 
which  all  assignments  for  British  load-line  certificates  are  made. 
While  some  varieties  of  these  three  types  have  very  evident 
peculiarities,  others  are  difficult  to  distinguish  by  casual  inspec- 
tion. This  may  be  demonstrated  by  an  attempt  to  estimate  from 
a  photograph  the  capacity,  gross  tonnage,  or  number  of  decks  of 
a  vessel.  The  observer  may  take  to  be  similar  two  vessels,  one  of 
which  is  five  times  the  size  of  the  other,  and  the  number  of  decks 
is  equally  difficult  to  determine;  for  this  reason  photographs 
are  only  occasionally  employed  here  as  illustrations.  The  load 
line  often  is  a  better  indication  of  the  main  class  of  a  vessel 
than  its  appearance.  The  statements  subsequently  made  that  cer- 
tain types  employ  lighter  forms  of  construction  do  not  imply 
structural  weakness.  All  of  these  types  are  equally  strong,  pre- 
sumably, in  proportion  to  their  dead  weight,  which  is  the  only 
fair  basis  of  comparison  of  a  number  of  types  designed  with  very 
different  purposes  in  view. 

It  may  further  be  said  that  since  the  primary  object  of  a  vessel 
is  to  earn  fares  and  freight,  success  must  be  judged  by  the  ability 
fully  to  load  the  vessel.  A  vessel  designed  as  a  combination 

2  Some  writers  prefer  to  consider  vessels  as  developing,  from  a  logical 
standpoint,  from  a  flush-deck  vessel  without  superstructure  to  one  with 
superstructure,  shade-deck  vessel,  awning-deck  vessel,  etc.,  up  to  the  full- 
scantling  vessel.  This  method  has  some  advantages  as  regards  facility  of 
explanation,  but  fails  to  emphasize  certain  structural  differences.  The 
second  deck  from  the  bottom  is  always  known  as  the  main  deck  and  the 
expression  "  upper  "  is  sometimes  used  as  denoting  the  topmost  deck,  but 
technically  refers  to  the  deck  above  the  main  deck. 


TYPES  OF  MERCHANT  VESSELS  69 

freight  and  passenger  ship  must  necessarily  be  at  a  disadvantage 
in  carrying  only  heavy  goods,  because  it  necessarily  performs  the 
journey  with  unoccupied  space  for  which  no  return  is  had,  and 
the  empty  space  is  even  subject  to  taxation.  The  object  of  the 
passenger  vessel  is  to  carry  a  maximum  number  of  passengers 
with  comfort  to  them.  For  the*  cargo  boat  the  following  are  es- 
sential : 

1.  A  low  registered  tonnage  compared  with  capacity. 

2.  Ample  space  available  for  water  ballast. 

3.  Large  hatchways. 

4.  Holds  as  free  as  possible  from  obstructions. 

5.  In  most  cases,  economical  operation  at  fair  speed. 

i.  Full-Scantling  Vessel. —  This  is  a  vessel  of  the  strongest 
construction,  in  which  the  structural  strength  is  maintained  up 
to  the  upper  deck.  It  may  have  one,  two,  three,  or  more  decks, 
and  a  depth  of  12  feet  or  40  feet,  but  this  structural  characteristic 
must  be  present  to  bring  it  within  the  full-scantling  class.  An  im- 
portant part  of  the  carrying  trade  is  concerned  with  commodities 
of  great  density  compared  with  their  bulk,  such  as  ore,  coal,  rails, 
machinery,  and  iron  and  steel  products.  By  loading  the  average 
vessel  with  goods  of  this  nature,  she  would  easily  be  brought 
down  to  minimum  freeboard  and  maximum  draft  long  before 
her  available  cargo  space  was  fully  occupied.  For  work  of  this 
nature,  therefore,  a  vessel  should  have  great  carrying  power  and 
strength  with  the  minimum  volume  or  space,  requirements  which 
are  most  nearly  fulfilled  by  the  full-scantling  type.  Likewise,  in 
some  trades  it  is  customary  to  carry  considerable  cargo  on  deck, 
and  consequently  the  necessary  structural  support  must  be 
furnished.  Lumber  might  be  cited  as  a  cargo  so  carried. 

(a)  Three-Deck  Vessel. —  Many  full-scantling  vessels  have 
three  decks  and  some  have  more.  The  following  midship  sec- 
tion illustrates  a  three-deck  vessel  and  it  will  be  noticed  that  the 
decks  from  the  keel  up  are  called  the  lower,  main,  and  upper 
decks. 

The  upper  deck  is  regarded  as  the  strength  deck  up  to  which 
the  full  structural  strength  must  be  maintained,  for,  the  vessel 
being  almost  wholly  immersed  when  fully  laden,  any  damage 
sustained  up  to  and  including  that  deck  jeopardizes  its  safety. 
The  expression  "  three-deck  vessel  "  arose  from  the  requirement 


70  MERCHANT  VESSELS 

of  a  classification  society  that  vessels  over  a  certain  depth  should 
have  three  decks  in  the  absence  of  other  equivalent  strength. 
Some  vessels  are  so  constructed,  and  formerly  it  was  common  to 


FlG.    25. —  THREE-DECK    VESSEL 

have  two  complete  decks  and  a  tier  of  hold  beams  below,  but  now 
a  vessel  of  this  character  often  has  only  one  laid  deck,  and  need 
not  possess  three  tiers  of  beams.  The  lowest  tier  may  be  dis- 
pensed with  by  the  deep  framing  and  web  framing  described  in  a 
former  chapter,  or  both  lower  tiers  may  be  replaced  by  one  of 


TYPES  OF  MERCHANT  VESSELS  71 

widely-spaced  extra-strength  beams  and  strengthened  framing. 
Where  only  one  steel  deck  is  required,  the  wooden  middle  deck 
may  be  eliminated  by  the  allowance  of  a  small  additional  free- 
board and  increased  framing  strength.  In  sum  and  substance  the 
expression  "  three-deck  vessel  "  refers  either  to  one  of  three  decks 


Reproduced  by  permission  from  Thomas  Walton,  "  Steel  Ships,"  Griffin  &  Co.,  London 
FlG.   26. —  TWO-DECK   VESSEL 

or  with  sufficient  depth  for  three  decks.  The  illustration  above 
shows  a  three-deck  vessel  in  which  the  lower  deck  is  dispensed 
with. 

The  three-deck  vessel  is  the  strongest  vessel  built  and  conse- 
quently has  a  minimum  freeboard,  maximum  immersion,  and 
greatest  displacement  and  carrying  power.  It  is  available  for  the 
carnage  of  commodities  of  great  weight  as  compared  with  size, 
and  for  trades  in  which  deck  cargoes  are  an  important  feature. 


72  MERCHANT  VESSELS 

The  early  types  of  three-deck  vessels  were  deep  and  narrow 
because  of  an  impression  that  breadth  contributed  exceptionally 
great  resistance  to  propulsion.  Within  recent  years  the  breadth 
has  been  considerably  increased,  however,  with  a  corresponding 
gain  in  stability  and  safety.  Additional  strength  above  the 
standard  results  is  no  decrease  of  freeboard,  since  this  is  already 
minimum,  but  such  reduction  may  be  obtained  by  the  addition  of 
superstructures.  As  a  vessel  grows  older  or  depreciates  in 
strength,  it  may  be  necessary  to  increase  the  freeboard,  in  connec- 
tion with  which  stability  and  the  vessel's  proportions  must  also 
be  considered.  In  larger  vessels  it  is  customary  to  have  at  least 
a  substantial  bridge  covering  half  the  length  amidships  for  the 
protection  of  the  engines. 

(b)  Two-Deck  Vessel. —  This  is  a  smaller  edition  of  the  three- 
deck  vessel  and  by  Lloyd's  rules  has  a  depth  of  less  than  24  feet 
from  the  top  of  the  keel  to  the  top  of  the  beam  at  the  center.     As 
in  the  three-deck  vessel,  two  actual  decks  need  not  exist  provided 
there  is  sufficient  space  for  them.     These  vessels  frequently  have 
superstructures  and  erections  on  deck,  as  described  hereafter,  for 
which  considerable  allowance  in  freeboard  is  made.     This  type  of 
vessel  is  employed  in  the  general  carrying  trade  where  cargoes  of 
great   density   are   frequently   offered    for   shipment,   but   where 
size  of  vessel  does  not  contribute  so  greatly  to  economical  opera- 
tion.    Figure  26  is  a  midship  section  of  a  two-deck  vessel. 

(c)  One-Deck  Vessel. —  In  structure,  this  is  similar  to  the  three- 
and  two-deck  vessels,  the  full  structural  strength  being  main- 
tained to  the  upper  deck.     By  Lloyd's  rules,  it  is  a  vessel  with 
a  depth  of  less  than  15  feet  6  inches  from  the  top  of  the  keel 
to  the  top  of  the  beam  at  the  center.     The  typical  modern  vessel 
with  one  deck  is  approximately  380  feet  in  length,   50  feet  in 
breadth,  and  28  feet  in  depth,  with  a  gross  tonnage  of  about  5000 
tons  and  from  6000  to  7000  tons  dead-weight  capacity  at  a  draft  of 
24  feet.     If  fitted  with  widely-spaced  pillars,  this  vessel  is  avail- 
able for  cargoes  of  any  ordinary  description,  whether  units  of 
great  volume  or  homogeneous  cargo,  such  as  grain,  in  bulk.     The 
expression  one-deck  vessel  is  frequently  applied  to  a  vessel  with 
sufficient  space  for  two  decks. 

(d)  Raised-Quarterdeck   Vessel. —  This  is  essentially  a  vessel 
of  the   full-scantling  type  inasmuch  as  the   structural  strength 


TYPES  OF  MERCHANT  VESSELS 


73 


is  maintained  up  to  the  upper  deck,  no  such  erection  as  a  raised 
quarterdeck  ever  being  built  on  vessels  of  the  spar-  or  awning- 
deck  type.  The  raised  quarterdeck  is  a  feature  customary  in  one- 
deck  and  two-deck  vessels  and  seldom  found  in  the  three-deck 
jvessel.  There  is  an  essential  difference  between  this  vessel  and 
the  light  spar-  and  awning-deck  types  described  hereafter.  The 
raised  quarterdeck  really  constitutes  an  increased  depth  over  the 
rear  portion  of  the  length,  and  thevafter  part  of  the  vessel  is 
structurally  equivalent  to  the  extra  depth  so  created.  This  vessel 
might,  therefore,  be  considered  as  composed  of  parts  of  two 
vessels  united  in  one,  one  of  said  vessels  being  from  3  to  6  feet 


FlG.   27. —  RAISED  QUARTERDECK   VESSEL 

greater  in  depth  than  the  other.  The  quarterdeck  must  be  care- 
fully and  strongly  joined  to  the  upper  deck,  as  this  line  of  divi- 
sion would  otherwise  be  a  place  of  great  strain.  The  average 
extent  of  the  rise  of  the  quarterdeck  over  the  main  deckls  about 
4  feet. 

Figures  27  and  28  make  clear  the  nature  of  the  raised- 
quarterdeck  erection,  if  an  integral  part  of  the  hull  can  be  called 
such. 

The  raised  quarterdeck  type  originated  by  reason  of  difficulties 
created  by  the  placing  of  engines  and  boilers.  If  placed  at  either 
bow  or  stern,  the  vessel  would  necessarily  trim  by  the  bow  or  stern 
respectively  when  not  loaded,  although  a  satisfactory  condition 
was  maintained  with  cargo  on  board.  On  the  other  hand,  placing 
boilers  and  engines  amidships  caused  difficulty  in  trimming  when 
the  vessel  was  loaded.  The  shaft  tunnel  occupied  a  relatively 


74 


MERCHANT  VESSELS 


large  space  in  the  after  portion  of  the  hull,  and  since  this  part 
of  the  hull  was  necessarily  built  on  finer  lines  than  the  fore  part, 
the  vessel  trimmed  by  the  head  when  loaded  with  homogeneous 
cargo  of  some  density.  There  was  no  trouble  where  heavy  cargo 
could  be  used  in  the  after  holds  for  trimming  and  where  the 
vessel  as  a  whole  carried  a  very  light  cargo,  the  ballast  tanks 
being  sufficient  properly  to  trim  the  vessel.  In  other  cases,  how- 
ever, great  difficulty  was  experienced  and  this  was  remedied  by 
increasing  the  depth  of  the  hold  space  above  the  engines  through 


FlG.    28. —  RAISED  QUARTERDECK    WITH    EXTENDED   BRIDGE 

the  medium  of  raising  the  quarterdeck.  This  type  of  vessel 
was  used  to  a  considerable  extent  in  the  Atlantic  cargo  trade  when 
provided  with  strong  deck  erections  and  no  passages  in  the  bridge- 
house.  In  brief  it  furnished  the  following  advantages: 

1.  A  better  trimmed  vessel  when  loaded 

2.  Additional  capacity 

3.  Considerable  buoyancy  credit  which  was  about  equivalent  to 

that  given  for  a  long  poop,  7  feet  high 

It  is  customary  to  protect  the  engines  by  a  bridge  because  of 
the  small  freeboard,  and  this  bridge  was  occasionally  extended 
almost  to  the  forecastle,  creating  a  between-decks  space  which  was 
available  for  the  carriage  of  light  goods,  but  the  increase  in 
registered  tonnage  was  relatively  heavy  for  this  spacers  compared 
with  the  extra  freight  which  could  be  earned  by  it.  Registered 
tonnage  has  always  had  great  influence  on  design  because  of  its 
use  as  a  basis  for  taxation.  This  type  was  due  principally  to 


TYPES  OF  MERCHANT  VESSELS 


75 


artificial  legislative  difficulties  and  not  to  commercial  require- 
ments. The  illustration  on  p^ge  28  shows  the  bridge  extended  for- 
ward to  create  this  modified  quarterdeck  vessel. 

The  following  illustration  shows  a  shorter  raised  quarterdeck 
which  was  sometimes  built.  It  is  necessary  to  distinguish  between 
this  short  raised  quarterdeck  and  the  superstructure  erected  at 
the  stern  of  a  vessel  known  as  the  poop.  The  former  is  an  integral 
part  of  the  whole  and  has  no  deck  laid  below  it,  while  the  latter 
is  simply  a  structure  built  upon  the  deck. 


FlG.    29. —  SHORT   RAISED    QUARTERDECK 

jf 

(e)  Shelter-Deck  Vessel—  The  expression  "  shelter  deck"  has 
been  applied  in  several  senses  and  its  meaning  consequently  con- 
fused, but  its  original  import  was  a  structure  built  upon  the  upper 
deck  and  extending  the  full  length  of  the  vessel,  either  wholly 
or  to  some  degree  unenclosed  and  designed  merely  to  afford  some 
shelter  from  the  elements.  The  term  is  also  employed  to  designate 
the  deck  above  the  upper  deck,  with  or  without  tonnage  openings, 
in  a  four-deck  vessel.  This  expression  is  most  commonly  used, 
however,  to  designate  a  three-deck  vessel  with  a  complete  erection 
fore  and  aft  on  the  upper  deck,  entirely  closed  from  the  sea  with 
the  exception  of  tonnage  openings  which  may  resemble  hatchways 
or  may  be  wide  enough  to  extend  to  the  sides  of  the  vessel.  The 
shelter  deck  is  usually  of  steel  or  iron  and  with  the  recent  ten- 
dency to  increase  the  strength  of  structure,  this  type  of  vessel 
has  come  to  resemble  an  awning-deck  vessel  in  construction,  the 
shelter  deck  being  more  and  more  built  into  the  hull.  The  fol- 
lowing is  an  illustration  of  the  shelter-deck  type. 

This  type  of  vessel  was  originally  due  to  the  development  of  the 


76  MERCHANT  VESSELS 

cattle  trade  in  which  considerable  general  cargo  was  carried, 
and  "unenclosed  space  in  the  shelter  deck  was  available  for  live 
stock.  This  space  was  exempted  from  the  gross  tonnage  of  the 
vessel  and  consequently  paid  no  dues  while  it  contributed  con- 
siderable credit  for  reserve  buoyancy  in  the  determination  of 
freeboard.  The  net  result  was  an  increased  capacity  on  a  small 
tonnage,  although  the  shelter-deck  space  was  gradually  more 
and  more  securely  enclosed  and  became  available  for  the  carriage 
of  light  cargo.  In  a  vessel  with  four  decks,  this  shelter  deck 
also  affords  a  between-decks  space  available  for  passengers  and 
miscellaneous  cargo. 


FlG.  30. — SHELTER-DECK  VESSEL 

(f)  Well-Deck  Vessel. —  Such  vessels  are  so  called  because  the 
space  between  the  bridge  and  forecastle,  being  enclosed  on  four 
sides  by  the  bridge,  forecastle,  and  sides  of  the  vessel,  forms  a 
well  which,  in  a  heavy  sea,  is  frequently  washed  by  the  waves. 
The  type  may  be  divided  into  two  classes.  In  the  first  place, 
the  raised-quarterdeck  type  of  vessel  resulted  in  the  existence  of 
a  well  of  this  nature  as  illustrated  by  the  diagrams  preceding. 
Secondly,  the  combination  of  a  long  poop,  bridge,  and  topgallant 
forecastle,  forms  a  similar  well,  as  illustrated  by  the  following- 
diagram  (Figure  32). 

The  well  is  left  open  and  uncovered  (i)  because  i-f  covered 
in  it  would  be  measured  and  yet  for  trimming  reasons  would  be 
unavailable  for  general  cargo,  and  (2)  because  the  vessel  would 
be  swept  by  waves  which  otherwise  fall  in  the  well  and  wash  out 
through  scuppers.  The  long  full  poop  extended  to  the  bridge 
house  was  intended  to  serve  in  a  lesser  degree  the  same  purpose 


78  MERCHANT  VESSELS 

as  a  raised  quarterdeck,  but  it  is  useful  only  for  light  cargo. 

This  type  was  formerly  very  popular.     In  1875,  30  per  cent 

of  the  total  tonnage  built  in  the  United  Kingdom  was  of  the  well- 

detk  type  and  31   per  cent  three-deck  vessels;  while  in   1890, 


FlG.   32. —  WELL-DECK  VESSEL 

these  two  types  formed  respectively  43  per  cent  and  18  per  cent 
of  the  total  tonnage  constructed.  This  characteristic  gave  to  the 
vessel  the  following  advantages: 

1.  A  single-deck  vessel  of  small  registered  tonnage  could  be 

cheaply  built  and  operated. 

2.  Such  a  vessel  could  be  well  filled  with  homogeneous  cargo, 

such  as  grain,  and  could  also  carry  dead  weight  in  a  favor- 
able position  relative  to  the  centers  of  gravity.       • 

3.  It  had  a  high  range  of  stability,  great  safety,  arid  was  easy 

to  keep  in  trim  either  loaded  or  light. 

4.  The  well  prevented  the  waves  from  sweeping  the  decks. 

In  recent  years,  this  vessel  has  been  largely  superseded  by  other 
types,  with  a  tendency  to  emphasize  flush-deck  vessels  with  super- 
structures. 

(g)  Full-Scantling  Vessel  with  Superstructures. —  Any  vessel 
may  be  equipped  with  superstructures  built  upon  the  upper  deck, 
the  three  most  common  being  the  forecastle,  bridge,  and  poop. 
Such  superstructures  are  very  valuable  as  affording  reserve 
buoyancy  and  this  at  the  places  where  most  valuable.  In  a  later 
chapter  it  will  be  shown  that  a  system  has  been  devised  for  giving 
credit  in  freeboard  for  such  erections  in  proportion  to  their 


TYPES  OF  MERCHANT  VESSELS 


79 


efficiency.     The  following  diagram  shows  a  vessel  equipped  with 
these  customary  superstructures. 

Without  considerable  freeboard,  a  flush-deck  vessel  would  be 
constantly  swept  by  the  seas.  The  waves  which  are  met  head  on 
would  wash  over  the  bows,  interfering  with  the  operation  of  the 
vessel,  washing  away  deck  fittings,  and  finding  their  way  below. 
To  obviate  this  the  sides  of  the  vessels  were  raised  at  the  bow 


.   33.  —  VESSEL   WITH    SUPERSTRUCTURES 


and  the  space  so  formed  closed  in  by  a  bulkhead,  the  whole  being 
rounded  off  to  a  hood  shape  which  was  termed  a  monkey  fore- 
castle. Subsequently  the  forecastle  developed  in  height  and  length 
and  afforded  accommodations  for  the  crew.  In  addition,  a  plat- 
form was  afforded  which  was  advantageous  in  working  the  anchor. 
This  enlarged  structure  is  termed  a  topgallant  forecastle.  Similar 
uncomfortable  results  were  occasioned  by  following  seas  wash- 
ing over  the  stern,  and  since  protection  was  desirable  for  the 
hand  steering  wheel  near  the  stern,  this  portion  of  the  vessel  was 
hooded  over  in  a  similar  manner  forming  a  short  poop.  This 
erection  also  developed  in  size  until  it  was  used  for  the  accommo- 
dation of  officers,  and  finally,  by  extension  into  a  long  poop,  might 
even  be  utilized  for  cargo.  The  bridge  was  originally  simply  an 
erection  in  the  center  of  the  vessel  for  the  use  of  navigating 
officers  and  the  lookout,  being  of  very  light  construction,  but 
later  it  was  practically  made  an  integral  part  of  the  structure  and 
served  as  a  protection  to  the  engines,  formerly  only  covered 
by  a  glazed  skylight.  In  recent  years,  the  bridge  has  been  ex- 
tended in  width  to  the  sides  of  the  vessel. 


8o 


MERCHANT  VESSELS 


(h)  Shade-Deck  Vessel. —  The  shade-deck  vessel  has  a  super- 
structure built  upon  the  full  length  of  the  upper  deck,  of  light 
structure  and  open  at  the  sides.  It  frequently  consists  merely  of 
light  deck  beams  supported  on  round  iron  stanchions  and  thus  is 
far  from  being  an  integral  part  of  the  hull.  It  is  frequently 
found  upon  large  passenger  vessels  but  gives  no  additional  reserve 
buoyancy.  This  deck  superseded  the  original  unstrengthened 
awning  deck.  An  illustration  is  given  below. 


FlG.   34. —  SHADE-DECK   VESSEL 

A  shade  deck  is  intended  only  as  a  shelter  for  passengers  and  to 
provide  a  promenade.  It  is  frequently  found  in  the  largest  cargo 
and  intermediate  steamers  where  it  does  not  reduce  seaworthiness 
and  affords  a  covered  shelter  in  combination  with  small  registered 
tonnage. 

(i)  Whaleback  Steamer.—  This  vessel,  as  indicated  by  the 
name,  has  a  design  above  water  bearing  crude  resemblance  in 
shape  to  a  whale.  It  is  distinctly  an  American  invention,  and 
a  vessel  of  this  type  first  crossed  the  Atlantic  in  1891.  The 
object  was  to  provide  a  seagoing  vessel  with  absolutely  clear 
decks,  so  that  there  were  no  deck  erections  to  be  carried  away 
by  the  sea.  The  peculiar,  rounded  form  of  the  deck  was  ex- 
pected to  break  the  force  of  the  sea  and  allow  it  to  escape  easily 
over  the  sides.  It  had  a  spoon-shaped  bow  and  in  two  respects 
resembles  the  turret  steamer,  next  to  be  described,  viz.,  in  the 
absence  of  fore-and-aft  sheer,  and  a  rounded  gunwale.  The  en- 
gines are  located  at  the  stern  of  the  vessel  behind  a  water-tight 
bulkhead.  The  hatchways  are  simply  holes  in  the  deck  with  no 


TYPES  OF  MERCHANT  VESSELS 


81 


coamings  and  closed  by  plates  bolted  through  the  deck.  The 
frontispiece  and  following  diagram  give  a  better  conception  of 
this  vessel  than  any  description. 

This  type  of  vessel  was  designed  to  carry  the  largest  amount 
of  cargo  with  the  lowest  registered  tonnage,  an  object  which 
was  fully  realized.  It  has  chiefly  been  utilized  for  the  carriage  of 
grain,  coal,  and  ore,  many  of  these  vessels  being  in  operation 
on  the  Great  Lakes  and  the  Pacific  Coast  and  a  few  having  been 
transferred  to  the  Atlantic  Coast  coal  trade.  Ore  cargoes  can 


FlG.    35. —  WHALEBACK    STEAMER 

be  stowed  to  great  advantage  in  the  cylindrical  holds  and  with 
the  hatches  bolted  down  these  vessels  are  exceptionally  sea- 
worthy. They  have  been  increased  gradually  to  450  feet  in 
length,  50  feet  in  breadth  and  27  feet  in  depth,  with  a  carry- 
ing capacity  of  approximately  9000  tons  at  a  draft  of  20 
feet.  They  exhibited,  however,  several  disadvantages.  Great 
difficulty  has  been  experienced  in  getting  about  the  decks  in 
bad  weather;  the  only  facilities  being  a  gangway  above  the 
deck,  separated  at  intervals  by  turrets.  Secondly,  the  spoon- 
shaped  bow  and  the  form  of  the  bottom  from  the  stem  for 
some  distance  aft  makes  the  hull  peculiarly  subject  to  the 
pounding  of  the  waves  in  a  head  sea.  These  vessels  have 
never  had  any  extensive  use  as  passenger  carriers,  although  the 
Christopher  Columbus  was  constructed  for  this  purpose  and  car- 
ried passengers  to  and  from  the  World's  Fair  on  the  Great  Lakes 
with  a  record  of  carrying  1,700,000  during  the  period.  This  work 


82 


MERCHANT  VESSELS 


involved  a  very  great  deal  of  embarkation  and  disembarkation 
and  it  was  found  possible  to  unload  as  many  as  one  thousand 
passengers  a  minute.  On  this  vessel,  five  steel  turrets  above 
the  main  deck  separated  a  promenade,  upper,  and  hurricane 
deck. 

( j )  Turret-Deck  Vessel. —  This  vessel  was  in  all  probability  an 
outgrowth  of  the  whaleback  steamer  and  has  been  very  success- 
ful, particularly  in  England,  where  one  shipyard  has  for  long 
periods  built  this  type  almost  exclusively.  It  is  similar  to  the 


Reproduced  by  permission  from  Thomas  Walton,  "  Steel  Ships,"  Griffin  &  Co.,  London 

FlG.    36. —  TURRET-DECK  VESSEL 

/ 

whaleback  steamer  in  two  respects,  viz.,  the  absence  of  fore- 
and-aft  sheer  and  the  rounded  gunwale,  and  in  other  respects 
radically  different.  The  form  of  the  vessel  below  water  is  the 
same  as  that  of  an  ordinary  vessel  and  on  the  main  deck  or 
harbor  deck  a  turret  erection  extends  continuously  from  stem  to 
stern.  The  sides  of  this  turret  bend  into  the  harbor  deck  and 
the  harbor  deck  into  the  vertical  sides  of  the  vessel  by  well- 
rounded  curves.  By  reason  of  the  increased  strength  given  to 
the  deck  by  curved  sides  and  large  angle  girders,  the  hold  pillars 
can  be  unusually  widely  spaced  with  the  resulting  advantage  in 
stowage  facilities.  The  latest  type  of  turret  vessel  has  approxi- 
mately a  30-foot  depth  without  hold  beams,  harbor  deck  beams, 


TYPES  OF  MERCHANT  VESSELS  83 

or  pillars,  leaving  the  hold  spaces  entirely  clear.  All  deck  open- 
ings and  erections  are  on  the  turret  deck,  which  is  the  working 
deck  while  at  sea.  In  the  later  vessels,  numerous  spaces  are 
provided  in  the  double  bottom  tanks  for  water  ballast,  and  to 
compensate  for  the  absence  of  sheer,  there  is  a  topgallant  fore- 
castle. Figures  36  and  37  are  illustrations  of  the  latest  type  of 
turret-deck  steamer. 

This  form  of  vessel  is  particularly  valuable  for  the  coal,  ore 
and  timber  trades  and  for  trades  in  wnich  long  voyages  must  be 


Reproduced  by  permission  from  Thomas  Walton,  "  Steel  Ships,"  Griffin  &  Co.,  London 
FlG.    37. —  TURRET-DECK   VESSEL 

made  in  ballast.  It  is  a  remarkably  good  dead-weight  carrier 
and  the  harbor  deck  can  be  used  for  the  carriage  of  lumber,  long 
iron  girders,  etc.  These  vessels  have  also  been  successfully  built 
to  carry  light  case  cargo  and  some  have  been  also  constructed 
with  between-decks  for  general  cargo.  In  addition,  the  type 
possesses  the  following  advantages : 

1.  It  is  exceptionally  strong  in  construction  and  the  turret  gives 
extra  longitudinal  strength. 

2.  An  absolutely  clear  hold  enables  advantageous  stowage  of 
large  bales,  case  cargoes,  and  bulk  cargoes. 

3.  A  large  amount  of  water-ballast  space  is  advantageous  on 
voyages  where  a  portion  of  the  journey  must  be  performed  empty. 


84  MERCHANT  VESSELS 

4.  There  is  no  opportunity  for  seas  finding  lodgment  on  the 
turret  or  harbor  decks. 

5.  Credit  for  reserve  buoyancy  is  obtained  on  a  basis  of  70  per 
cent  of  the  turret  volume. 

6.  As  every  part  of  the  structure  contributes  to  the  strength 
and  there  are  no  breaks  in  the  continuity  of  the  decks,  there  is  a 
considerable  saving  in  weight  as  compared  with  ordinary  boats  of 
the  same  dimensions. 

7.  The  turret  deck  is  from  10  to  12  feet  above  the  load  line, 
furnishing  protection  to  the  important  parts  of  the  vessel,  pre- 


FlG.   38. —  TRUNK-DECK   VESSEL 

venting  the  seas  from  breaking  over  the  ship  and  keeping  the 
navigating  platform  clear  of  water. 

8.  The  harbor  deck  is  said  to  tend  to  reduce  rolling. 

9.  Under  the  Suez  Canal  measurement  rules,  the  vessel  has  the 
benefit  of  having  the  turret  considered  as  an  erection  with  the 
consequent  measurement  of  only  little  more  than  half  the  cubic 
capacity. 

10.  Wheareas  in  the  ordinary  vessel  homogeneous  cargoes  tend 
to  subside  and  consequently  shift,  the  turret  forms  a  feeder  from 
which  the  cargo  can  shift  into  the  lower  holds,   keeping  them 
completely   full.     The   shifting  in   the   turret   is   of   small   con- 
sequence as  regards  stability. 

11.  The  depth  of  the  turret  may  be  increased  aft  to  enable  the 
vessel  to  trim  by  the  stern  in  the  same  manner  as  a  raised  quarter- 
deck vessel. 

12.  Cargo  can  be  shot  into  the  holds  without  trimming. 


TYPES  OF  MERCHANT  VESSELS  85 

(k)  Trunk-Deck  Vessel. —  This  vessel,  like  the  turret-deck 
vessel,  is  similar  to  the  ordinary  vessel  up  to  the  gunwale,  but 
on  the  main  deck  a  trunk  erection  extends  from  poop  to  bridge 
and  from  bridge  to  forecastle,  the  height  of  which  is  approxi- 
mately 7  feet.  Unlike  superstructures  this  forms  a  continuous 
erection.  This  trunk  erection  is  approximately  half  the  beam  of 
the  vessel  in  width,  the  space  below  the  trunk  is  entirely  open 
down  to  the  lower  hold,  and  all  hatchways,  ventilators,  and  deck 


Reproduced  by  permission  from  Thomas  Walton,  "  Steel  Ships,"  Griffin  &  Co.,  London 
FlG.   39. —  TRUNK-DECK   VESSEL 

openings  are  on  the  trunk  deck  or  superstructure.  Of  recent 
years  great  development  has  taken  place  in  the  trunk  steamer. 
It  is  now  usually  fitted  with  a  trunk  extending  the  full  length 
of  the  vessel,  with  the  height  varying  from  7  to  10  feet,  and  the 
breadth  of  from  50  to  75  per  cent  of  the  beam  of  the  vessel. 
The  trunk  is  thus  much  wider  than  formerly  and  the  vessel  is 
now  usually  fitted  with  a  forecastle  and  sometimes  a  full  poop 
but  no  bridge.  If  desirable,  the  deck  may  be  carried  through 
under  the  trunk  and  the  latter  made  an  unenclosed  and  conse- 
quently an  unmeasured  space.  Vessels  are  also  .^equently 
furnished  with  water-ballast  tanks  at  the  sides  of  the  trunk.  The 


86 


MERCHANT  VESSELS 


hold  space  is  entirely  clear  except  for  widely  spaced  hold  pillars. 
Figures  38  and  39  are  illustrations  of  trunk-deck  vessels,  one 
showing  a  vessel  with  water-ballast  tanks  at  the  sides. 

Like  the  turret-deck  vessel  this  ship  was  designed  for  large 
dead-weight  and  cubic  capacity  on  a  small  net  registered  tonnage 
and  may  be  used  for  general  cargoes  or  for  coal  and  ore.  It 
has  a  similar  advantage  as  regards  free-hold  space,  and  water- 
ballast  tanks  at  the  side  increase  the  immersion  when  light  and 
promote  the  efficiency  of  the  propeller  and  helm,  giving  an  easier 
motion  in  a  sea  way.  As  in  the  case  of  the  turret,  the  trunk 


FlG.   40. —  SELF-TRIMMING   VESSEL 

is  an  excellent  feeder  to  the  main  holds,  contributing  to  the  satis- 
factory trimming  of  the  vessel.  The  main  deck  outside  of  the 
trunk  is  well  fitted  for  carrying  timber,  cattle  or  other  deck 
cargoes.  This  design  has  sometimes  been  employed  for  carrying 
oil  in  bulk. 

"NJ  (1)  Self-trimming  Vessel. —  This  is  an  ordinary  vessel  with  an 
erection  about  five  feet  high,  extending  the  length  of  the  ship  and 
having  a  top  breadth  of  about  half  the  beam  of  the  ship,  which 
forms  a  navigating  deck.  The  sides  of  the  erection  slope  from 
the  navigating  deck  to  within  two  feet  of  the  gunwale,  in  order 
to  increase  the  self-trimming  capacity  of  the  ship.  All  hatches, 
funnels,  and  deck  openings  are  on  the  navigation  deck  and  hold 
beams  are  dispensed  with.  The  erection  has  free  communication 
with  the  hold  for  trimming  purposes,  the  self-trimming  idea  being 
the  distinctive  feature  of  the  vessel.  As  the  sloping  side  of  the 
navigating  deck  offers  insufficient  protection  from  in-rushing  seas, 
a  closed  iron  bulwark  is  fitted  to  the  navigation  deck  which  keeps 
this  deck  dry  and  affords  protection  in  navigation.  The  above 
is  an  illustration  of  this  type  of  vessel. 


TYPES  OF  MERCHANT  VESSELS 


(m)  Cantilever  Vessel. —  This  is  a  vessel  very  similar  in  some 
respects  to  the  self -trimming  vessel  but  with  important  structural 
differences.  An  ordinary  vessel  of  its  type  would  belong  to  the 
three-deck  type.  Several  feet  before  reaching  the  deck,  however, 
the  frames  bend  inward  and  are  projected  diagonally  forward  to 
the  base  of  a  top  fore-and-aft  girder,  extending  continuously  all 
along  the  length.  Th^te  is  formed,  therefore,  on  each  side  a  tri- 


Reproduced  by  permission  from  Thomas  Walton,  "  Steel  Ships,"  Griffin  &  Co.,  London 
FlG.   41. —  CANTILEVER  VESSEL 

angular  space,  two  sides  of  which  are  formed  by  the  shell  and 
the  deck  plating,  and  the  third  side  is  furnished  by  the  plating 
over  the  bent-in  frames.  The  word  cantilever  is  a  combination 
of  "  cant  "  meaning  angle  and  the  word  "  lever."  In  this  vessel, 
the  deck  is  supported  by  a  leverage  obtained  from  the  angle  to 
the  frame,  hence  the  name.  Figures  41  and  42  are  illustrations  of 
this  type  of  vessel. 

This  vessel  possesses  the  following  advantages : 

1.  An  absolutely  clear  hold  space. 

2.  Greatly  increased  water-ballast   space,   sometimes   amount- 
ing to  nearly  one-third  of  the  total  dead  weight. 

3.  The  water  ballast  is  distributed  over  the  length  of  the  ship 
instead  of  being  concentrated   in  the  center   as  where  midship 
deep  tanks  are  used.     While  some  space  is  thereby  lost,  this  is 
the  very  space  which  is  most  difficult  to  fill  with  bulk  cargoes  in 
ordinary  vessels. 


88 


MERCHANT  VESSELS 


4.  No  trimming  expenses. 

5.  The  construction  permits  of  long,  broad  hatches. 

6.  The  full  width  deck  area  is  preserved  for  deck  cargoes, 
(n)   Corrugated  Vessel. —  This  is  an  ordinary  tramp  steamer  in 

dimensions  and  engine  power  with  two  corrugations  j^unning  along 
each  side  between  bilge  and  water  line,  and  extending  from  the 
turn  of  the  bow  to  the  turn  of  the  quarter.  These  do  not  project 
much  but  through  their  effect  on  the  stream  and  wave  action 


Reproduced  by  permission  from  Thomas  Walton,  "  Steel  Ships,"  Griffin  &  Co.,  London 
FlG.    42. —  CANTILEVER  VESSEL 

around  and  under  the  vessel,  they  are  said  to  save  otherwise 
wasted  energy  and  to  have  the  effect  of  bilge  keels  in  making 
the  vessel  steadier.  The  space  for  bulk  cargo  is  greater  than  in 
the  ordinary  vessel  by  the  space  of  the  corrugation  but  the  ton- 
nage remains  unaltered,  and  a  faster  speed  is  said  to  be  attained 
withja  smaller  coal  consumption. 

(o)  Tank  Vessel. —  These  vessels  have  been  constructed  in 
various  ways,  all  designed  to  economize  the  carriage  of  fluid 
cargoes,  such  as  petroleum  products  and  molasses.  The  earliest 
variety  was  an  ordinary  cargo  vessel  with  tanks  fitted  into  the 
holds ;  a  cheap  method  of  production  which  entailed  considerable 
loss  of  space,  and  increased  weight.  In  modern  practice  the 


TYPES  OF  MERCHANT  VESSELS  89 

sides  and  deck  of  the  vessel  form  integral  portions  of  the  tank 
and  the  vessel's  bulkheads  form  the  other  two  sides  of  the  tank. 
In  other  words,  instead  of  a  vessel  containing  one  or  more 
tanks,  the  vessel  itself  is  a  large  subdivided  tank.  A  newer  type 
of  oil-carrying  vessel  consists  of  a  hull  of  ordinary  construction 
fitted  with  cylindrical  tanks,  and  is  thus  a  reversion  to  the  earlier 
form.  This  is  a  cheaper  method  of  construction,  but  its  principal 
claim  to  distinction  is  that  by  the  removal  of  the  tanks  the  vessel 
is  converted  into  an  ordinary  carrier.  The  cylindrical  tanks,  how- 
ever, cause  the  loss  of  some  oil-carrying  space. 


FlG.   43.— CORRUGATED  VESSEL 

In  two-deck  vessels  the  second  deck  forms  the  crown  of  the 
oil  tanks,  and  in  vessels  of  sufficient  depth  to  require  three  tiers 
of  beams  the  lower  tier  is  usually  dispensed  with.  Oil  vessels 
have  been  built  with  an  inner  skin  but  apparently  with  little  ad- 
vantage, as  the  space  formed  by  the  outer  and  inner  shell  serves 
to  harbor  gases. 

The  engines  may  be  located  either  amidships  or  at  the  stern, 
but  the  latter  location  is  preferred  because  of  more  complete 
isolation  from  the  cargo  and  consequently  greater  safety.  In  a 
vessel  with  engines  situated  aft  the  compartment  abaft  of  the 
collision  bulkhead  is  used  for  general  cargo.  The  protection  for 
the  engines  is  obtained  by  a  long  poop  and  in  the  Atlantic  trade 
this  frequently  extends  as  far  forward  as  the  deck  house,  amid- 
ships. The  crew  is  housed  in  a  topgallant  forecastle.  These 
vessels  may  be  equipped  with  spar  or  shelter  decks,  but  the  latter 
has  no  tonnage  openings  and  is  a  shelter  deck  in  name  only. 

It  is  necessary  to  mention  some  of  the  characteristics  of  oil  as 
a  cargo,  since  they  illustrate  the  distinctive  features  of  the  tank 
vessel.  ( i )  The  gases  from  petroleum  products,  especially  crude 


90  MERCHANT  VESSELS 

oil,  become  highly  explosive  when  brought  in  contact  with  the 
atmosphere.  Consequently  the  tanks  must  be  carefully  con- 
structed to  prevent  leakage  and  a  system  provided  for  drawing 
off  the  gases  emitted,  which  are  heavier  than  the  atmosphere. 
They  are  usually  blown  out  of  the  oil  tanks  by  steam  injections. 
The  engines  must  be  effectively  isolated  from  the  cargo.  (2) 
Oil  is  subject  to  expansion  and  contraction  with  increases  and 
decreases  of  temperature.  An  increase  of  20  degrees  Fahrenheit 
causes  an  increase  in  the  volume  of  oil  of  approximately  i  per 
cent,  and  since  variations  of  from  40  to  60  degrees  are  quite 
common  on  ordinary  voyages  it  is  evident  that  some  means  must 
be  provided  for  absorbing  this  expansion.  Cold,  on  the  other 
hand,  causes  contraction  and  creates  empty  space  in  the  tank, 
which  is  conducive  to  rolling.  Tank  vessels  are,  therefore,  pro- 
vided with  expansion  tanks  or  trunkways  fitted  between  decks,  ex- 
tending fore-and-aft  over  the  main  hold  tanks,  which  usually  hold 
about  15  per  cent  of  the  vessel's  oil  cargo  and  which  serve  as 
space  for  expansion  or  as  feeders  to  counteract  contraction  and 
keep  the  main  holds  full.  (3)  While  the  ordinary  cargo  is  sup- 
ported by  the  transverse  and  longitudinal  framing,  the  oil  cargo, 
like  all  fluids,  exerts  pressure  in  all  directions,  extending  in  some 
vessels  to  the  outside  shell.  Oil-tightness  and  strength  are,  there- 
fore, important  characteristics  of  the  tank  vessel,  and  for  it  the 
Isherwood  system  has  been  extensively  used  because  of  the  re- 
duction in  weight  and  extra  longitudinal  strength  thereby  at- 
tained. (4)  A  fluid  cargo  is  inert  and  accentuates  the  rolling  of 
the  vessel,  besides  exerting  heavy  pressure  with  the  motions  of 
the  ship.  A  longitudinal  bulkhead  is,  therefore,  provided  extend- 
ing all  fore-and-aft  and  dividing  the  cargo  into  two  parts,  so 
as  to  minimize  this  effect.  (5)  The  process  of  loading  and  un- 
loading must  be  carefully  performed  because  any  listing  of  the 
vessel  will  be  increased  by  the  shifting  of  the  fluid  cargo  to  the 
lowered  side.  It  is  apparent  that  full  tanks  are  an  important 
consideration  in  connection  with  safety,  and  that  stability  is  a 
prime  factor  in  this  type  of  ship. 

The  early  method  of  transporting  oil  was  in  cases  and  barrels. 
The  bulk  system,  however,  permits  of  faster  loading  and  dis- 
charging, so  that  an  amount  of  petroleum  requiring  otherwise 
4  or  5  days  for  loading  or  unloading  (say  1700  tons)  can  be 
handled  in  bulk  in  6  hours.  Likewise,  there  is  great  economy  in 


TYPES  OF  MERCHANT  VESSELS  91 

space,  resulting  in  increased  earning  power.  A  ton  of  oil  in  bar- 
rels occupied  approximately  80  cubic  feet  of  space,  while  a  ton 
of  the  ordinary  type  of  cargo  required  to  bring  a  three-deck  vessel 
down  to  her  load  draft  does  not  require  more  than  50  feet,  in- 


Reproduced  by  permission  from  Thomas  Walton,  "  Steel  Ships,"  Griffin  &  Co.,  London 
FlG.   44. —  TANK   VESSEL 

dicating  the  wastefulness  of  the  barrel  method.  In  bulk  a  ton  re- 
quires no  more  than  40  cubic  feet.  There  are  now  over  300 
large  steamers  and  50  sailing  vessels  engaged  in  carrying  oil  in 
bulk.  Above  is  shown  an  illustration  of  a  typical  tank 
vessel. 


92  MERCHANT  VESSELS 

t- 

(p)  Refrigerator  Vessel. —  While  the  processes  used  are  es- 
sentially the  same,  we  must  distinguish  between  the  refrigera- 
tion facilities  in  ocean  passenger  steamers,  which  are  confined  to 
supplying  an  insulated  chamber  for  fresh  meat  and  supplies  con- 
sumed on  the  voyage,  and  the  more  extensive  appliances  in  re- 
frigerating steamers  carrying  cargoes  of  frozen  or  chilled  meats. 

Two  systems  are  employed  in  the  cargo  trade.     The  freezing 


0/I°;U!U 


o!U 


Reproduced  by  permission  from  Thomas  Walton,  "  Steel  Ships,"  Griffin  &  Co.,  London 
FlG.  45. —  TANK  VESSEL 

process  is  suitable  for  cargoes  such  as  mutton,  which  is  commonly 
shipped'  in  frozen  whole  carcasses  which  remain  frozen  stiff 
throughout  the  voyage.  The  temperature  of  the  hold  is  kept  at 
15  degrees  Fahrenheit  without  injury  to  the  meat.  Beef,  on  the 
other  hand,  is  greatly  injured  by  freezing  and  is  shipped  in  a 
chilled  state,  the  temperature  of  the  hold  being  maintained  just 
above  freezing  point.  Great  care  is  required  to  keep  the  tempera- 
ture within  one  degree  of  the  required  point,  and  many  refine- 
ments are  introduced  into  the  refrigerating  apparatus  with  this 
object  in  view.  The  freezing  process  is  also  unsuitable  for  other 
commodities  such  as  butter,  milk,  vegetables,  and  fruit. 

The  requirements  for  refrigeration  are  briefly  an  insulated  hold 
and   a    refrigerating   machine.     Charcoal,   silicate,    pumice,   and 


TYPES  OF  MERCHANT  VESSELS  93 

granulated  cork  are  used  for  insulation.  The  refrigerating  ma- 
chine is  usually  located  between-decks  or  in  a  deck  house  near 
the  insulated  holds,  but  it  may  be  placed  in  the  main  engine  room. 
Various  systems  of  refrigeration  are  employed,  principally  the 
following : 

(1)  Cold-Air  or  Dry- Air  System. —  Air  drawn  from  the  hold  i.> 
compressed,  which  makes  it  hot,  and  the  heat  is  abstracted  by 
passing  the  air  through  a  coil  surrounded  by  sea  water  and  a  coil 
surrounded  by  cold  air.     When  again  allowed  to  expand  it  be- 
comes intensely  cold  and  is  then  returned  to  the  hold  through 
trunkways.     The  passage  through  the  coil  surrounded  by  cold  air 
causes  the  loss  of  its  moisture,  hence  the  name  "  dry  air." 

(2)  Carbonic- Anhydric  System. —  Carbonic  acid  gas  is  com- 
pressed instead  of  air  and  through  compressing  and  cooling  be- 
comes a  liquid.     This  is  passed  into  a  coil  placed  in  a  tank  of  brine 
(chloride  of  calcium).     Here  it  is  allowed  to  expand,  resumes 
its  gaseous  form,  and  is  chilled  to  10  degrees  Fahrenheit.     The 
surrounding  brine  also  becomes  chilled  and  is  withdrawn  at  zero 
Fahrenheit  and  circulated  through  long  coils  in  the  holds. 

(3)  Ammonia  System. —  This  is  practically  the  same  except 
that  ammonia  gas  is  used  instead  of  carbonic  acid  gas. 

(4)  Direct-Expansion  Battery  System. —  It  is  sometimes  found 
advisable  to  bring:  the  air  from  the  hold  to  a  special  chamber  to 
be  cooled  and  then  return  it  to  the  holds  at  the  proper  tempera- 
ture. 

The  dry-air  system  is  suitable  only  for  frozen  cargoes  where 
the  precise  degree  of  cold  is  unimportant,  while  the  carbonic-acid 
and  ammonia-gas  systems  have  both  advantages  and  disadvantages. 
The  former  is  difficult  to  operate  in  tropical  climates  because 
sea  water  used  for  cooling  is  sometimes  too  warm  and  great 
pressure  is  required  to  liquefy  at  a  high  temperature.  But  volume 
for  volume  carbonic  acid  gas  is  heavier  than  ammonia  and  is 
consequently  a  more  efficient  refrigerating  medium.  Therefore, 
the  ammonia  compressor  must  be  large  with  consequent  loss  of 
space.  Ammonia  cannot  be  used  in  the  main  engine  room  be- 
cause the  slightest  leakage  fills  the  room  with  noxious  gases. 
Carbonic  acid  gas,  while  dangerous  in  quantities,  is  respirable  in 
small  quantities  without  inconvenience,  but  is  odorless  and  leaks 
are  difficult  to  detect. 

Insulation  is  of  some  disadvantage  in  a  vessel  which  must  also 


94  MERCHANT  VESSELS 

be  used  in  other  trades.  The  insulation  space  is  lost  for  other 
cargoes,  screws  cannot  be  used  for  compressing  cargoes  of  wool 
and  heavy  dead-weight  cargo  cannot  be  carried  without  danger 
of  damaging  the  insulation.  Refrigeration  has,  nevertheless,  be- 
come an  important  factor  in  modern  life,  which  is  seen  from 
the  fact  that  immense  frozen  and  chilled  meat  trades  have  grown 
up  in  New  Zealand  and  the  Argentine.  The  Shaw,  Savill  & 
Albion  Company,  operating  between  London  and  New  Zealand,  is 
said  to  transport  over  2,800,000  carcasses  per  annum  and  in 
England  20  pounds  of  imported  meat  per  head  is  consumed  a  year. 
Some  of  these  refrigerating  vessels  reach  a  length  of  470  feet 
with  a  capacity  of  100,000  carcasses  of  10,000  tons  dead  weight. 
The  following  is  an  illustration  of  a  typical  refrigerator  ship. 

(q)  Steam  Schooner. —  A  type  of  vessel  almost  peculiar  to 
the  Pacific  Coast  deserves  to  be  included  in  this  list.  The  steam 
schooner  is  a  development  of  the  sailing  schooner  and.  like  its 
predecessor,  is  mainly  used  in  the  lumber  trade.  They  are 
heavily  built  vessels,  having  the  motive  power  and  superstructure 
well  at  the  stern,  and  were  described  by  Mr.  Frank  W.  Hibbs, 
in  a  paper  before  the  Society  of  Naval  Architects  and  Marine 
Engineers,  as  follows : 

These  vessels  are  built  similarly  to  the  sailing  schooner,  with 
greater  proportionate  beam  than  the  ordinary  steamer,  with  high  free- 
board, great  sheer  forward,  a  topgallant  forecastle,  and  raised  quarter- 
deck. They  have  low  power  and  are  built  to  very  heavy  scantlings, 
and  are  the  staunchest  vessels  that  are  seen  on  the  coast.  They  carry 
large  deck  cargoes  of  lumber,  and  are  regarded  as  the  most  profitable 
type  of  coasting  cargo  vessels. 

Their  general  structure  resembles  that  of  a  sailing  vessel  but 
their  motive  power  is  exclusively  steam.  Between  the  forecastle 
and  the  bridge  located  far  aft  there  is  an  immense  unobstructed 
deck  space  available  for  lumber.  On  page  95  is  shown  a  plan  of  a 
vessel  of  1600  tons  capable  of  transporting  1,500,000  feet  of 
lumber. 

2.  Awning-Deck  Vessel. —  Thus  far  we  have  been  considering 
/only  vessels  in  which  the  full  strength  of  scantlings  is  maintained 
through  the  depth.  But  where  maximum  dead-weight  capacity  is 
not  the  primary  consideration  this  is  unnecessary,  and  the  con- 
struction is  accordingly  modified  as  in  the  awning-  and  spar-deck 
ships.  The  former  is  a  three-deck  vessel  with  a  lower  main  deck 


96  MERCHANT  VESSELS 

and  awning  deck.  It  is  the  lightest  type  of  overseas  boat,  and 
the  full  structural  strength  is  maintained  only  up  to  the  main  deck, 
the  awning  deck  being  of  very  light  construction.  As  originally 
understood,  it  was  merely  a  light  continuous  superstructure  from 
stem  to  stern  on  the  main  deck,  but  early  awning  decks  were  too 
light  and  vessels  later  tended  to  approach  a  class  intermediate  be- 
tween the  original  awning-deck  type  and  a  full-scantling  vessel. 
This  has  caused  confusion  between  the  awning-deck  vessel  and 
the  spar-deck  vessel,  a  heavier  type  described  later.  In  a  com- 
plete superstructure  vessel  of  awning-deck  type,  the  freeboard 
is  measured  from  the  second  deck,  but  by  reason  of  the  awning 
deck  the  freeboard  is  very  much  less  than  for  a  flush-deck  vessel 
of  the  same  dimensions  as  the  hull  proper  of  the  awning-deck 
vessel.  It  must  be  emphasized  that  the  awning  deck  is  an  integral 
part  of  the  hull,  and  not  a  superstructure,  such  as  a  forecastle, 
poop,  or  shelter  deck.  It  might  be  crudely  described  as  a  com- 
bination of  the  lower  part  of  the  hull  of  a  full-scantling  two-deck 
vessel  combined  with  the  upper  hull  of  a  very  lightly  constructed 
ship.  The  difference  in  freeboard  obtained  by  the  awning  deck 
is  relatively  much  greater  for  small  vessels  than  for  large  vessels. 
A  flush-deck  vessel  of  8-feet  depth  with  a  freeboard  of  12  inches 
would  have  as  an  awning-deck  vessel  a  freeboard  of  only  i  inch, 
a  reduction  of  91  per  cent.  On  the  other  hand,  a  flush-deck  vessel 
with  a  depth  of  50  feet  and  a  freeboard  of  10  feet  2  inches,  has 
a  reduction  of  23  per  cent.  This  is  reasonable  because  the  depth 
of  the  small  vessel  is  doubled  by  the  awning,  while  that  of  the 
larger  is  increased  only  16  per  cent.  With  increased  strength 
above  the  standard  allowance  in  freeboard  is  made.  An  illus- 
tration of  the  midship  section  of  an  awning-deck  vessel  would  be 
useless  in  this  connection  because  the  scale  would  be  too  small  to 
show  the  relative  size  of  scantlings  above  and  below  the  main 
deck. 

As  distinguished  :from  the  heavy  cargoes  for  which  the  full- 
scantling  vessel  is  particularly  suitable,  we  have  many  bulky 
cargoes  of  small  density,  as,  for  example,  cotton  and  many  forms 
of  package  freight.  With  this  type  of  cargo  all  the  available  space 
of  a  full-scantling  vessel  could  be  occupied  and  the  vessel  not  im- 
mersed to  its  maximum  draft.  What  is  wanted,  therefore,  is  a 
vessel  with  considerable  volume,  less  strength,  and  consequently 
smaller  immersion,  displacement,  and  carrying  power.  In  other 


TYPES  OF  MERCHANT  VESSELS 


97 


words,  a  smaller  proportion  of  the  enclosed  volume  is  used  for 
displacement  at  the  load  draft.  It  would  be  impossible  to  bring 
the  full-scantling  vessel  down  to  the  load  line,  the  excessive 
strength  would  be  unnecessary  and  costly,  and  the  awning-deck 
vessel  has  a  larger  freeboard  and  drier  decks.  It  is,  therefore, 
available  for  the  carriage  of  heavy  cargo  in  the  lower  holds  with 
passengers  or  package  freight  between  decks.  The  original  very 
light  type  is  now  used  for  purely  passenger  steamers. 

(a)  Partial  Awning-Deck  Vessel.-^-  Sometimes  the  awning  deck 
does  not  extend  the  full  length  of  the  vessel.  Such  vessels  may 
be  built  either  with  or  without  a  poop  as  illustrated  below,  and 


FlG.  47. —  AWNING-DECK   VESSEL 

the  partial  awning  deck  is  useful  for  the  carriage  of  light  cargo, 
cattle,  or  passengers,  reserve  buoyancy,  and  protection  to  the 
engines.  Where  the  partial  awning  deck  is  brought  in  harmony 
structurally  with  the  strength  of  the  raised  quarterdeck  less  free- 
board is  required  than  for  standard  awning-deck  vessels. 

3.  Spar-Deck  Vessel. —  This  is  a  three-deck  vessel  with  a 
lower,  main  and  spar  deck,  the  upper  portion  of  the  hull  sup- 
porting the  spar  deck  being  of  lighter  construction  but  more  sub- 
stantial than  in  the  awning-deck  type.  The  uppermost  or  spar 
deck  is  considered  as  the  strength  deck,  as  in  the"tnree-deck  vessel, 
and"  for  the  same  reason.  Up  to  the  main  deck,  the  vessel  is 
practically  similar  to  a  two-deck  vessel  except  that  the  spar  deck 
•constitutes  so  valuable  an  erection  or  rather  integral  part  of  the 
hull  that  allowances  are  made  in  calculating  length  to  depth. 
Thus  a  vessel  of  16  depths  to  its  length  is  considered  as  15  which 
results  in  a  great  saving  in  freeboard,  which  is  measured  down- 
ward from  the  spar  deck.  Frequently  these  vessels  are  built  in 


98  MERCHANT  VESSELS 

excess  of  requirements  and  by  carrying  the  reverse  frames  up  to 
the  spar  deck  and  adding  material,  the  vessel  might  be  brought 
up  to  the  three-deck  standard  with  consequent  lessening  of  free- 
board. The  standard  height  of  the  spar  deck  between  decks  is 
7  feet. 

This  vessel  is  of  a  type  intermediate  between  a  full-scantling  and 
awning-deck  vessel  and  is  available  for  mixed  cargoes  and  these 
of  moderate  density.  The  between-deck  space  under  the  spar- 
deck  was  originally  intended  only  for  passengers  but  later  was 
strengthened  for  freight.  This  type  of  vessel  has  been  very 
popular  in  recent  years. 

\/VUnrigged  Craft. —  We  may  briefly  consider  several  types  of 
craft.  These  include,  barges,  tank  barges,  scows,  lighters,  dredges, 
rafts,  etc.  Of  these  the  most  important  is  the  barge,  a  name 
applied  to  vessels  of  many  styles.  Frequently  the  barge  is  merely 
an  old  steam  or  sailing  vessel  whose  usefulness  for  the  original 
purpose  has  disappeared ;  on  the  other  hand,  it  may  be  a  specially 
constructed  steel  vessel  adapted  for  a  particular  purpose.  These 
vessels  have  fulfilled  two  needs:  they  have  displaced  steam 
and  sailing  vessels  to  some  degree  in  the  carriage  of  very  heavy 
bulk  commodities,  and  have  supplemented  the  work  of  these 
vessels  by  relieving  them  of  products  for  which  the  barge  is 
more  suitable.  More  than  one-half  the  United  States'  tonnage 
of  this  character  is  used  on  the  Atlantic  Coast  and  more  than 
one-quarter  on  the  Mississippi  River,  where  the  principal  com- 
modities carried  in  this  type  of  vessel  are  coal,  iron  ore,  pig  iron, 
lumber,  shingles,  railroad  ties,  sand,  stone,  gravel,  brick,  cement, 
lime,  and  similar  heavy  commodities.  The  number  and  tonnage 
of  tugs  and  unrigged  vessels  constitute  practically  one-half  of 
the  total  for  the  Atlantic  and  Gulf  Coasts  and  95  per  cent  of 
the  tonnage  of  the  Mississippi  River.  The  following  tables  will 
give  an  idea  of  the  importance  of  such  vessels  in  the  United 
States  according  to  the  census  compiled  in  1916  and  published  in 
1919. 

The  total  tonnage  of  all  vessels  in  the  United  States  was 
estimated  by  this  census  to  be  12,249,990,  and  the  tonnage  of 
the  unrigged  vessels  amounts  to  4,981,254  or  over  one-third  of 
this  total.  A  considerable  decrease  is  noted  in  the  tonnage  of  un- 
rigged vessels  between  the  years  1906  and  1916,  but  this  is  largely 
accounted  for  by  the  decline  in  the  canal  boats  on  the  Erie  Canal 


TYPES  OF  MERCHANT  VESSELS 


99 


TABLE  1 

NUMBER,  GROSS  TONNAGE,  AND  VALUE  OF  UNRIGGED  VESSELS  IN 
THE  UNITED  STATES 


1916 

1906 

1889 

Number  of  vessels 

20  7ii 

2O  267 

l6  O77 

Gross  tonnage  

4  08  I  2^4 

7  I2Q  6"?  I 

iujyo/ 

4  Q77  7^6 

Value    . 

07.210.760 

/f**y»vo* 

64.004.240 

T->y/o>oo'-' 

22.271  .OS  7 

TABLE  2 

UNRIGGED  VESSELS  IN  THE  UNITED  STATES  BY  GEOGRAPHICAL 
DIVISIONS,  1916 


Number 

Gross  tonnage 

Value 

Atlantic  and  Gulf  Coasts 

IO  772 

2  876  278 

$68  772  Q8Q 

Pacific  Coast  and  Alaska  .    . 

i  677 

2C7  C6l 

8  063  288 

Great  Lakes  and  St.  Lawrence 
Mississippi  River  and 
tributaries   

857 

C  C?Q 

•"JO'J^1- 

181,611 

I  SOI  S72 

8,157,884 

0  887  44Q 

Canals  and  other  inland  waters 
Total  

1,470 
2O  711 

168,312 

4  o8l  2^4 

2,378,150 
Q7  2I0.76o 

All  vessels  in  United  States  .  . 

37,894 

12,249,990 

959,925,364 

and  the  decrease  on  the  Mississippi  River  in  the  number  of  coal 
barges  in  the  big  Pittsburgh  fleets.  Table  2  shows  the  Atlantic 
Coast  and  Mississippi  River  as  the  leading  sections  of  the  country 
in  this  type  of  craft.  The  figures  indicate  that  its  tonnage  has 
increased  about  27  per  cent  on  the  Atlantic  Coast  from  1906  to 
1916,  and  about  64  per  cent  on  the  Pacific  Coast  during  the  same 
period.  A  considerable  portion  of  the  Pacific  Coast  increase  is 
accounted  for  by  Alaska  and  the  construction  of  barges  for  the 
petroleum  trade.  On  the  Great  Lakes,  Mississippi  River,  and 
other  inland  waters,  there  were  decreases  of  14  per  cent,  64  per 
cent,  and  29  per  cent,  respectively.  These  figures  do  not  include 
schooner  barges,  which  were  placed  in  the  sailing-vessel  class 
by  the  census  authorities. 

One  may  distinguish  the  small  barges  from  the  larger  and 
heavier  types  used  for  seagoing  purposes.  The  latter  consist 
principally  of  "  schooner  barges,"  a  name  applied  because  they 
are  fitted  with  a  limited  amount  of  canvas.  In  fact,  the  sails  are 
little  used  for  propulsion  except  in  case  of  necessity  to  avoid 


ioo  MERCHANT  VESSELS 

absolute  helplessness  when  cut  loose  from  the  towing  vessel. 
These  are  built  to  carry  over  3000  tons  at  times  and  may  be  towed 
singly  or  in  fleets  of  two  or  three.  The  towing  is  either  by  tug, 
by  a  towing  steamer  adapted  to  the  purpose  or  by  a  loaded 
steamer.  The  latter  method  is  comparatively  little  used,  being 
uneconomical  as  compared  with  the  two  former  methods.  The 
main  source  of  building  material  for  these  vessels  continues  to  be 
wood,  although  steel  barges  are  also  being  constructed. 

The  advantages  of  towing  unrigged  craft  are  principally  the 
following : 

1.  The  lower  initial  cost  of  construction  of  the  vessel  and  in 
some  cases  the  utilization  of  otherwise  valueless  hulls.     At  one 
time  it  was  even  the  practice  to  build  barges  for  one  or  two  trips 
on  the  Mississippi  River,  selling  them  as  lumber  or  using  them 
for  other  purposes  upon  reaching  destination. 

2.  The  complete  utilization  of  propulsive  machinery,  the  tow- 
ing vessel  being  able  to  go  on  with  its  work  while  the  barges  are 
being  loaded  or  unloaded. 

3.  A  reduction  in  the  crew  otherwise  necessary,  only  three 
men  being  required  for  a  large  seagoing  barge. 

4.  Greater  regularity  of  service  than  is  possible  with  sailing 
vessels,  which  previously  furnished  the  cheap  transportation. 

5.  Ease  and  speed  in  loading  and  unloading. 

6.  Low  cost  of  repairs. 

The  disadvantages  of  this  method  of  transportation  are : 

1.  Interference   with   work  by   rough  weather.     Until   recent 
years  the  loss  of  life  and  cargo  on  these  vessels  was  dispropor- 
tionately large  due  to  their  helplessness  in  bad  weather,  overload- 
ing and  the  lack  of  adequate  life-saving  facilities. 

2.  As  a  result  of  the  above  conditions  the  marine  insurance  pre- 
miums are  high  and  many  barges  and  even  tugs  sail  uninsured. 

3.  Their  limitations  as  far  as  kind  of  cargo  is  concerned. 

Special  tank  barges  are  provided  for  the  transportation  of  petro- 
leum, by  fitting  barges  with  tanks  in  a  manner  similar  to  steamers. 
Some  of  these  vessels  have  a  capacity  of  2,500,000  gallons  of  oil. 
Seventeen  such  vessels,  built  of  metal  and  aggregating  about 
20,000  gross  tons,  were  added  to  the  Pacific  Coast  fleet  between 
1906  and  1916.  These  vessels  are  completely  equipped  with 
engines  for  pumping,  etc.,  and  automatic  towing  gear  operated  by 
hydraulic  machinery. 


TYPES  OF  MERCHANT  VESSELS:^  >f\\  \  //,  101 

A  considerable  amount  of  lumber  is  moved  in  the  form  of  rafts 
by  merely  tying  together  the  cargo  and  floating  it  downstream 
or  towing  it,  especially  in  the  Mississippi  valley  and  on  the 
Pacific  Coast.  Such  rafts  have  also  been  used  for  open  sea 
navigation  in  favorable  weather. 

Other  types  of  unrigged  vessels,  such  as  scows,  lighters,  float- 
ing docks,  floating  lighthouses  and  similar  harbor  craft  belong 
more  properly  to  a  volume  on  harbor  management. 3 

Modern  Developments. —  In  closing  it  might  be  stated  that 
the  principal  developments  in  cargo  vessels  of  recent  years  have 
been  the  following: 

1.  In  order  to  obtain  the  maximum  cargo  the  lines  of  the  ves- 
sels have  been  filled  out,  increasing  the  block  coefficient,  until 
the  extreme  is  reached  in  Great  Lakes  steamers  with  a  figure  of 
88  per  cent. 

2.  Portions  of  the  vessel  above  water  which  make  no  useful 
contribution  to  cargo-carrying  capacity  but  would  be  measured 
are    cut    down    to    the    minimum    requisite    for    buoyancy    and 
stability. 

3.  To  provide  for  return  journeys  empty  or  partially  loaded, 
large   water-ballast  spaces  have  been  provided  abreast  of   and 
above  the  cargo  spaces. 

4.  Holds  have  been  cleared  of  obstructions  so  that  stowage 
space  is  unbroken. 

5.  Hatches  have  been  increased  in  size  and  number. 

REFERENCES 

1.  HUEBNER,  G.  G. :     Ocean  Steamship  Traffic  Management.     D.  Ap- 

pleton  &  Co.,  New  York,  1920.  Chap.  V.  (The  business  or- 
ganization of  the  line  and  the  tramp  steamer  and  the  methods 
of  operation;  charter  parties;  ship  brokers.) 

2.  SMITH.  J.  R. :     Organisation  of  Ocean  Commerce.     Publications 

of  University  of  Pennsylvania,  Philadelphia,  1905.  Chaps.  II 
and  III.  (Relative  advantages  and  economies  of  line  and 
tramp  operation.) 

3.  SPARKS,  T.  A.:     "  Relation  of  the  Contractor  or  Speculator  to  the 

World's  Ocean  Transportation  Problem."  Annals  of  American 
Academy  of  Political  and  Social  Science,  September,  1914, 
pp.  232-236.  (An  explanation  of  the  necessity  of  the  speculator 
in  ocean  space,  particularly  in  the  tramp  business.) 

3  See  MacElwee  and  Taylor,  Wharf  Management,  Stevedoring,  and  Stor- 
age, D.  Appleton  &  Co.,  New  York,  1921. 


102  ' '  t  * ' ;.    i  ;M£ RJCHANT  VESSELS 

4.  JOHNSON,   E.    R.,   and   HUEBNER,    G.    G. :    Principles   of   Ocean 

Transportation.  D.  Appleton  &  Co.,  New  York,  1918.  Chaps. 
XXI  and  XXII.  (On  the  factors  governing  ocean  freight 
rates  and  passenger  fares.) 

5.  HUEBNER,  S.  S. :     "  Steamship  Line  Agreements  and  Affiliations." 

Annals  of  American  Academy  of  Political  and  Social  Science, 
September,  1914,  pp.  75-111.  (On  the  universal  prevalence  of 
agreements  and  associations  and  the  various  methods  employed 
to  enforce  agreements  and  prevent  competition.) 

6.  HOLMS,  A.  C. :    Practical  Shipbuilding.     Longmans,  Green  &  Co., 

London,  1916.  Vol.  I,  Chap.  VII.  (On  freeboard  and  the  load 
line.) 

7.  HOLMS,  A.  C. :    Practical  Shipbuilding.    Longmans,  Green  &  Co., 

London,  1916.  Vol.  II.  (Plans  and  diagrams  of  types  of 
vessels  and  their  parts.) 

8.  WALTON,   THOMAS:    Steel  Ships.    Griffin   &   Co.,   Ltd.,   London, 

1918.  Chap.  VI.  (On  types  of  vessels  according  to  construc- 
tion characteristics,  with  illustrations  and  diagrams.) 

9.  MONTGOMERIE,  J.  i     "  Arrangement  and  Construction  of  Oil  Ves- 

sels."   Cassier's  Magazine,  1911,  Vol.  40,  pp.  737-752. 


CHAPTER  VI 
TYPES  OF  MARINE  ENGINES 

The  present  chapter  initiates  a  discussion  of  the  various  types 
of  vessels  according  to  motive  power  by  describing  the  evolution 
of  steam  as  a  means  of  propulsion  and  the  kinds  of  marine  en- 
gines now  in  use.  The  succeeding  chapter  will  deal  with  oil- 
burning  and  internal-combustion  engines.  Improvements  in 
steam  navigation  are  appropriately  divided  into  two  parts :  ( I )  the 
problem  and  period  of  effective  steam  generation,  in  which  the  goal 
is  the  production  of  the  maximum  energy  from  a  given  quantity 
of  fuel;  and  (2)  the  problem  and  period  of  steam  utilization,  in 
which  the  object  is  economically  to  apply  the  energy  produced  so 
as  to  achieve  the  maximum  results.  The  maximum  result  desired, 
of  course,  may  be  either  extremely  high  speed  or  the  carriage  of  a 
large  tonnage  at  a  reasonable  cost. 

It  is  profitless  to  consider  the  controversy  as  to  the  first  suc- 
cessful application  of  steam  to  marine  propulsion;  many  individ- 
uals contributed  to  the  development  of  a  satisfactory  engine.  For 
a  considerable  time,  as  has  been  previously  described,  the  sailing 
vessel  and  the  steam  vessel  were  in  competition,  and  for  some 
time  the  enormous  coal  consumption  of  the  steam  engine  made  its 
use  impossible  save  on  the  shortest  voyages.  So  uncommon  was 
the  steamer  that  one  was  chased  by  a  revenue  cruiser  f oFa  day 
in  the  belief  that  it  was  a  ship  on  firej  The  earliest^type  of  en- 
gine of  any  prominence  was  the  beam  engine,  familiar  to-day  in 
the  ferryboat.  This  was  suitable  for  river  and  lake  navigation 
but  impossible  for  ocean  travel  because  ( i )  it  made  the  vessel  top- 
heavy  and  (2)  the  beam  protruded  through  the  deck  which  for 
ocean  service  had  to  be  covered  in. 

It  was,  however,  easy  to  adapt  the  beam  engine  by  convert- 
ing it  into  the  side-lever  engine.  This  is  accomplished  by  placing 
the  beam  below  instead  of  above  the  cylinder  and  as  far  down  in 
the  ship  as  possible.  The  illustration  on  page  105  shows  the  appli- 
cation of  this  type  of  engine  to  a  paddle-wheel  steamer.  For  many 

103 


104  MERCHANT  VESSELS 

A  CLASSIFICATION  OF  MARINE  ENGINES 

I.  Utilization  of  steam  pressures 

A.  Simple,  utilizing  steam  at  one  pressure 

{Double  expansion      1  utilizing   steam   at 
Triple  expansion        Lboth  high  and  low 
Quadruple  expansion  pressures 
II.  Action  of  steam 

A.  Single-acting,     the  steam  acting  on  one  side  of  pis- 

ton and  the  return  of  the  piston  not 
being  a  working  stroke 

B.  Double-acting,    the  steam  acting  alternately  on  both 

sides  of  the  piston  and  both  strokes 
being  working  strokes 

III.  Transmission  of  power 

A.  Direct-acting,     the  crank-pin  of  the  revolving  shaft 

being    directly    connected    with    the 
piston 

B.  Indirect-acting,  a  lever  being  interposed  between  the 

piston      and     the      connecting      rod. 
Either  with  or  without  a  beam 

IV.  Construction  of  cylinder 

A.  Oscillating  cylinder,  the  cylinder  moving  to  accom- 

modate   itself    to    the    action   of 
other  parts  of  the  machinery 

B.  Stationary  cylinder,  in  various  positions,  such  as 

1.  'Horizontal       fTT     .  . 

2.  Vertical "pnght 

T    ..  I  Inverted 

3.  Inclined 

V.  Use  of  exhaust  steam 
A.     Noncondensing 

_,    ^  .  f  Surf  ace  condensation 

B.  Condensing <|  T   .      . 

^  Injection  condensation 

VI.  Manner  of  applying  steam 

A.  Reciprocating  engine,  where  the  steam  works  on  a 

piston 

B.  Turbine  engine,  where  the  steam  works  on  movable 

revolving  blades 

1.  Impulse-and-reaction  turbine 

2.  Impulse  turbine 


TYPES  OF  MARINE  ENGINES 


105 


years,  in  fact  until  the  introduction  of  the  screw  propeller  about 
1860,  this  was  the  recognized  type  of  marine  engine.  The  Sirius, 
Great  Western,  Britannia,  Hibernia,  America,  Arabia  and  Persia, 
all  prominent  early  transatlantic  steamers,  were  equipped  with  it, 
Its  working  parts  were  well  balanced,  it  was  strong  and  could 
easily  be  used  for  auxiliary  work,  such  as  air  pumps,  but  it  was 
heavy,  increasingly  expensive  as  it  became  more  complicated,  con- 


FlG.  48.  —  SIDE-LEVER  ENGINE     - 


sumed  entirely  too  much  space  and  a  tremendous  quantity  of 
coal.  The  Sirius,  crossing  the  Atlantic  under  steam  power  for  the 
first  time,  exhausted  the  coal  supply  and  burned  her  spars  in  order 
to  reach  port.  These  engines  were  supplied  with  cylinders  from 
60  to  72  inches  in  diameter,  boilers  with  pressures  of  from  10  to 
12  pounds  per  square  inch  and  from  400  to  750  horse  power. 
The  speed  attained  was  from  7  to  9  knots  per  hour.  By  1862 
this  type  of  engine  had  been  developed  to  4000  horse  power  with 
a  speed  of  13  knots  per  hour,  having  cylinders  8  feet  4l/2  inches 
in  diameter  and  a  boiler  pressure  of  25  pounds  per  square  inch. 
No  more  than  two  cylinders  were  ever  used. 

During  the  period  of  transition  from  the  paddle  steamer  to  the 
screw  propeller  the  oscillating  engine  was  introduced.     The  beam 


106  MERCHANT  VESSELS 

or  lever  was  eliminated  by  connecting  the  piston  of  the  cylinder 
directly  with  the  crank  shaft.  This  required  that  the  cylinders 
sway  or  oscillate  from  side  to  side,  being  placed  on  trunnions  in 
the  same  manner  as  a  cannon.  The  condenser  was  placed  be- 
tween the  two  cylinders.  The  illustration  below  shows  clearly 
the  principle  and  is  interesting  also  as  showing  the  earliest  of 
such  engines.  The  oscillating  engine,  in  order  to  be  applied  to 
the  screw  propeller,  had  to  be  supplemented  by  gearing  in  order 


Reproduced  by  permission  from  E..  K.  Chatterton,  "  Steamships  and  Their  Story," 
Cassell  &  Co.,  London 

FlG.   49. —  OSCILLATING   ENGINE 

to  give  the  propeller  shaft  the   requisite   speed  —  three  to   six 
times  as  much  as  was  necessary  for  paddle  wheels. 

This  type  of  engine  had  the  advantage  of  saving  considerable 
space,  and  was  light  in  weight.  It  was  employed  in  the  Great 
Eastern,  a  transatlantic  vessel  nearly  twice  the  size  of  any  vessel 
previously  built ;  the  China,  a  screw  steamer  of  1862 ;  and  the 
Candia,  a  Peninsular  and  Oriental  Company  vessel.  From  two 
to  four  cylinders  were  used,  with  diameters  of  from  70  to  80 
inches,  from  2500  to  5000  horse  power,  and  a  boiler  pressure  of 


TYPES  OF  MARINE  ENGINES 


107 


from  22  to  30  pounds  per  square  inch.  The  coal  consumption  of 
the  Great  Eastern  was  350  tons  per  day,  greater  than  some  of  the 
large  liners  of  the  twentieth  century.  The  exhausted  steam  was 
condensed  in  a  separate  cylinder  by  a  jet  of  cold  water,  a  system 
which  cannot  be  used  with  a  boiler  pressure  of  over  35  pounds. 
Thus  far,  the  developments  have  mainly  been  to  utilize,  as  far 
as  possible,  the  energy  produced  by  the  more  or  less  unsatisfactory 
engines.  For  paddle-wheel  steamers  direct-acting  engines  were 


FlG.   50.— OSCILLATING  GEARED  ENGINE 

employed.  For  the  screw  propeller  these  were  unsatisfactory  be- 
cause with  low-pressure  boilers  the  speed  of  the  piston  was  insuf- 
ficient to  give  the  required  revolutions  to  the  propeller  shaft. 
Gearing  was  therefore  introduced  to  attain  this  result.  Strangely 
enough  the  next  development  was  away  from  gearing  and  back  to 


Tntrod 


uc- 


the_d  j rect-a^tionj£ngineT     1  his  was  made  possible  by  the 
tion  of  the  double-expansion  or  compound  engine. 

The  compound  enc/ine  allows  the  steam  to  enter  one  cylinder 
at  high  pressure  and,  after  having  moved  the  piston  in  this  cylin- 
der, to  escape  into  one  or  more  other  larger  cylinders  where  the 
pistons  are  moved  by  direct  expansion.  Triple-expansion  was  in 
use  shortly  before  1890  and  quadruple-expansion  was  introduced 
about  1900.  Considerably  more  work  is  thus  performed  by  the 
same  steam  at  much  lower  cost.  The  pressure  was  increased 
from  30  to  between  60  and  100  pounds  per  square  inch  by  the 
compound  engine,  and  from  125  to  160  pounds  by  the  triple-ex- 
pansion engine,  and  from  210  to  220  pounds  by  the  quadruple- 
expansion  engine.  Also,  the  coal  consumption  was  reduced  by 


io8  MERCHANT  VESSELS 

the  compound  engine  to  one-half  what  it  had  been  in  the  most 
economical  previous  engine.  From  a  coal  consumption  of  4.7 
pounds  per  horse  power  per  hour  in  1840  there  was  a  decline 
to  3.75  pounds  in  1852  by  improvement  of  boilers;  to  2.5  pounds 
in  1873  by  the  compound  engine;  to  1.5  in  1892  through  the 
triple  expansion.  The  multiple-expansion  principle,  therefore, 
contributed  to  the  development  of  marine  propulsion  both  through 
the  improvement  in  the  creation  of  energy  and  through  the  utiliza- 
tion of  such  energy  by  making  possible  the  direct-action  engine. 

Along  with  greater  steam  pressure  went  a  change  in  methods 
of  condensation.     The  jet  condenser  was  unsatisfactory  because 


FlG.   SI. —  TRUNK  ENGINE 

salt  water  was  introduced  into  the  boilers  and  the  intense  heat 
caused  a  coating  of  sulphate  of  lime.  A  surface  condenser  is  now 
used,  consisting  of  a  number  of  brass  tubes  through  which  a 
stream  of  cold  water  circulates.  These  pipes  are  thereby  kept 
cool  and  condense  the  exhaust  steam  fed  to  them  by  the  cylin- 
ders. The  condensed  steam  may  then  be  drawn  off  by  a  feed 
pump  and  again  supplied  to  the  boiler. 

The  direct-action  engines  made  possible  by  the  two  preceding 
improvements  were  of  various  types.  In  the  trunk  engine  the 
cylinder  is  placed  horizontally  at  right  angles  to  the  propeller 
shaft.  The  trunk  passes  through  a  steam-tight  stuffing  box  in  the 
cylinder  cover  and  is  wide  enough  to  allow  for  the  oscillations  of 
the  connecting  rod.  The  illustration  above  gives  an  idea  of  this 
type  of  engine,  which  became  unsatisfactory  as  steam  pressure 
increased,  because  of  the  increased  friction  of  the  stuffing  boxes. 
The  cylinders  of  the  trunk  engine  were  also  sometimes  placed 


TYPES  OF  MARINE  ENGINES 


109 


upright  with  the  piston  acting  upward,  sometimes  inverted  diag- 
onally, and  sometimes  the  horizontal  and  inverted  arrangements 
were  combined. 

The  engine  which  has  thus  far  been  the  most  important  in 
modern  steam  navigation,  dating  from  about  1870,  was  the  in- 
vgrteo1.  d^^^clipja^.,jecjpracatin^_e.n^ui|§.  The  cylinders  are 
inverted  above  the  propeller  shaft  and  the  connecting  rods  from 
the  pistons  are  directly  attached  to  the  cranks  of  the  shaft.  As 
stated  previously,  the  efficiency  of  tKe  reciprocating  engine  was 
greatly  increased  by  the  introduction  of  the  compound  engine, 
utilizing  steam  at  high  and  low  pressure.  The  triple-expansion 
engine  still  further  elaborated  this  idea  into  three  stages  of  utili- 
zation—  high,  medium,  and  low  pressure  —  and  the  three-crank 
design  of  this  engine  has  retained  its  popularity  until  the  present 
time.  It  enabled  the  development  of  a  higher  initial  steam  pres- 
sure of  from  175  to  200  pounds,  and  a  more  complete  utilization  of 
energy.  By  extending  the  principle,  the  quadruple-expansion  en- 
gine was  developed  which  increased  the  steam  pressure  about  8 
per  cent.  While  the  triple-expansion  type  is  still  useful  in  cargo 


Wilhelm 
der  Grosse 

Kensington 

Deutschland 

Triple 

Quadruple 
expansion 

Quadruple 
expansion 

Purpose      .  . 

Mail  steamer 

Pass,  and 

Fast  steamer 

Owner      

North  Ger- 

cargo 
steamer 
International 

Hamburg- 

Number  of  engines  
Total  indicated  horse 
power   

man  Lloyd 

2 

28,000 

Navigation 
Company 

2 

8,300 

American 
Line 

2 

34,000 

Number  of  revolutions  .  . 
Boiler  pressure                .  . 

78 
i?8 

86^ 
200 

78 
214 

Number  of  cylinders  
Diameter  of  cylinders 
High  pressure  

4'     454" 

4 

2'      I*/2" 

rt*                     —-        n-**~ 

6 

3'      %o" 
_  3'      %o" 

Medium  pressure  

•f    <y4" 

""?        iK" 

6'    i%o" 

Low  pressure  

8'    y2" 

4'    4//' 

6'      2" 

8'    79/io" 
8'  io%o" 

Stroke       

5'    8^" 

4'    6" 

8'  io%0" 
6'      %o" 

Speed  of  ship  

22  knots 

1  6  knots 

23  knots 

i  io  MERCHANT  VESSELS 

carriers  on  shorter  voyages,  the  quadruple  engine  has  superseded 
it  for  large  vessels  and  passenger  ships,  particularly  on  long  voy- 
ages. Its  advantages  are  (i)  ability  to  take  advantage  of  higher 
steam  pressure;  (2)  superior  smoothness;  (3)  development  of 
greater  speed. 

Its  disadvantages  as  compared  with  the  triple-expansion  engine 
are  increased  weight,  cost  and  upkeep.  The  added  first  cost  and 
more  difficult  supervision  are  factors  of  particular  importance  in 
cargo  vessels.  In  all  types  of  reciprocating-engines,  however,  at 
least  three  limitations  to  increasing  efficiency  were  encountered. 
Improvements  in  steam  consumption  were  becoming  difficult,  the 
size  of  the  power  units  was  becoming  tremendous,  and  any 
reduction  in  weight  involved  an  increase  in  the  speed  of  rotation 
with  its  attendant  difficulties.  Thus  the  conditions  were  favorable 
to  an  entirely  new  method  of  steam  application. 

TURBINE  ENGINES 

It  would  hardly  be  correct  to  speak  of  the  deficiencies  of  the 
reciprocating  piston-type  engine  in  view  of  the  great  advancement 
in  navigation  made  possible  by  its  use.  Nevertheless,  it  was  inevi- 
table that  improvements  should  be  desired  and  accomplished,  and 
of  these  the  most  important  was  the  application  of  the  turbine  prin- 
ciple. This  is  not  unlike  the  water  turbine  in  essence,  the  power 
being  generated  by  the  impact  of  steam  upon  movable  blades. 
Turbine  engines  of  marine  efficiency  may  be  divided  into  two 
main  classes,  depending  upon  the  manner  in  which  the  steam  is 
applied  to  the  movable  blades,  namely  ( i )  the  impulse-and-reaction 
type,  and  (2)  the  impulse  type.  In  both  the  impulse-and-reaction 
type  and  the  impulse  type  two  problems  must  be  solved :  ( i )  The 
steam,  when  issuing  under  pressure,  must  take  a  single  direction 
and  not  disperse;  (2)  the  velocity  of  the  moving  parts  of  the 
mechanism  must  be  great  enough  efficiently  to  utilize  the  velocity 
of  the  steam.  To  take  full  advantage  of  a  jet  of  steam  in  a 
turbine  with  a  single  wheel  would  give  the  moving  parts  a  periph- 
eral velocity  of  2000  feet  per  second  which  would  be  very  dif- 
ficult to  gear  down  to  a  workable  speed  and  would  require  mate- 
rials not  now  available  to  withstand  the  resulting  stress  on  the 
moving  parts.  These  problems  are  best  illustrated  by  comparing 
two  of  the  principal  engines  now  in  use. 


TYPES  OF  MARINE  ENGINES  in 

Impulse  Type. —  The  principle  involved  is  to  apply  a  jet  of 
steam  to  movable  blades  in  such  a  manner  that  the  impact  will 
cause  the  movable  blades  and  the  drum  to  which  they  are  attached 
to  revolve.  The  pressure  energy  is  thereby  converted  into  veloc- 
ity energy,  and  the  velocity  attained  from  steam  is  far  greater 
than  that  developed  with  water  because  of  the  lesser  density  of 
steam.  The  steam  streams  from  one  end  to  the  other  through 
the  ringlike  space  between  a  cylinder  and  a  revolving  drum  con- 
tained therein.  To  the  casing  which  surrounds  the  drum  is  at- 
tached a  series  of  parallel  rings  of  fixed  guide  blades  projecting 
inward,  and  between  these  rings  of  guide  blades  and  attached 
to  the  drum, is  a  series  of  movable  blades  which  revolve  with 
the  drum.  The  passage  of  the  steam  through  the  spaces  thus 
arranged  causes  the  movable  blades  and  the  drum  to  which  they 
are  attached  to  revolve.  The  result  is  in  effect  an  operation  the 
reverse  of  an  electric  fan.  In  the  fan  the  revolution  of  the  blades 
creates  a  current  of  air  while  in  the  turbine  a  current  of  steam 
causes  a  revolution  of  the  blades. 

Impulse-and-Reaction  Type. —  This  is  exemplified  by  the  Par- 
sons turbine.  Its  efficiency  was  demonstrated  by  an  experimental 
vessel  of  100  tons  called  the  Turbinia  in  1897.  The  De  Laval 
turbine  with  one  wheel  of  moving  blades  was  inadequate  for  work 
on  a  large  scale.  Parsons  divided  the  expansion  of  the  steam, 
which  produces  the  velocity,  into  a  series  of  steps  or  stages,  en- 
abling full  utilization  of  the  energy  of  the  steam  without  making 
the  velocity  of  the  moving  blades  too  great.  The  range  of  pres- 
sure through  which  the  steam  passes  in  any  one  stage  is  not 
great  enough  unduly  to  increase  the  velocity.  At  each  step  in  the 
expansion  the  steam  streams  through  a  ring  of  fixed  guide  blades 
and  is  thrown  upon  a  ring  of  movable  blades.  At  each  step  there 
is  a  reaction  as  well  as  impulse  effect.  The  steam  loses  pressure 
as  it*^passes  each  ring  of  moving  blades  and[  each  pair  of  fixed- 
and  moving  blade  rings  virtually  constitutes_ji_separate  turbine, 
There  may  be  from  100  to  200  stages  in  large  marine  turbines. 
As  the  steam  progresses  and  loses  pressure  its  energy  is  fully 
utilized  down  to  the  lowest  point  attainable.  Marine  turbines  are 
divided  into  high  and  low  pressure  parts,  usually  three  in  number 
and  each  driving  a  separate  propeller  shaft.  In  many  turbines 
the  rotary  speed  developed  is  very  high  and  where  too  great  to  be 
directly  imparted  to  the  propeller  shaft  a  system  of  gearing  is 


112 


MERCHANT  VESSELS 


introduced  to  reduce  the  revolutions  to,  say,  one-tenth  on  the  main 
shaft. 

In  the  Curtis  turbine  no  drop  in  pressure  occurs  while  the 
steam  is  passing  through  the  rings  and  the  only  change  in  velocity 
is  due  to  friction,  thereby  eliminating  the  reaction  element.  While 
the  Parsons  turbine  utilizes  the  energy  of  the  steam  without  un- 
duly increasing  the  speed  of  revolution  by  dividing  the  heat  drop 


Reproduced   by  permission  from  E.    K.    Chatterton,   "  Steamships   and   Their  Story," 
Cassell  &  Co.,  London 

FlG.   52. —  PARSONS   TURBINE 

into  stages,  the  Curtis  accomplishes  this  result  by  allowing  the 
energy  to  expend  itself  upon  a  series  of  rings  or  blades,  usually 
three  in  number.  The  steam  is  guided  from  one  set  of  blades  to 
another,  in  the  sense  that  the  steam  acquires  new  velocity  at  each 
set  of  rings  and  gives  this  up  to  the  moving  blades  of  that  step, 
passing  to  a  second  set  of  nozzles  in  which  it  undergoes  a  second 
drop  in  pressure  and  acquiring  velocity  which  it  imparts  to  a 
second  set  of  movable  blades.  Thus,  the  Curtis  may  be  regarded 
as  two  turbines  with  their  shafts  connected  and  the  Parsons  as  a 
single  turbine  in  which  many  changes  in  pressure  occur  in  the 
passage  of  the  steam  from  one  blade  to  another. 

The  turbine  at  first  proved  especially  adaptable  to  large  and 
fast  vessels,  though  later  applied  to  slower  speeds.     The  con- 
siderations leading  to  its  adoption  for  passenger  liners  and  faster 
cargo  vessels  were  the  following : 
^   I.  The  adaptability  of  the  turbine  to  greater  power  develop- 


TYPES  OF  MARINE  ENGINES  113 

ment  in  a  single  unit.  As  has  been  shown,  the  triple-expansion 
developed  into  quadruple-expansion  only  at  the  expense  of  in- 
creased weight,  complexity,  and  coal  consumption,  while  the  in- 
creased  efficiency  was  relatively  small.  Increased  size  and  speed 
were  desired,  and  the  turbine  made  these  possible.  The  Adriatic, 
built  in  1906,  was  709  feet  long  with  quadruple  engines  of  15,000 
horse  power,  speed  15  knots;  the  Deutschland,  built  in  1900, 
was  663  feet  long  with  quadruple  engines  of  34,000  horse  power 
and  a  speed  of  23  knots ;  the  Lusitama,  built  1907,  was  785  feet 
long,  equipped  with  Parsons  turbines  of  68,000  horse  power  and 
with  a  speed  of  25  knots. 

This  concentration  of  power  would  probably  have  been  im- 
possible save  for  the  turbine. 

2.  Less  weight  of  machinery  and  coal.     One  writer  has  com- 
pared the  machinery  weight  of  a  four-screw,  triple  series  turbine 
with  water-tube  boilers  of  1913  with  a  twin-screw  triple-expan- 
sion engine,  cylindrical  boilers,  of  1893,  both  Atlantic  passenger 
vessels,  and  finds  the  former  is  but  60  per  cent  of  the  latter  in 
weight.     A    similar   comparison    for  cargo   vessels    showed   the 
1913  engine  weighed  but  84  per  cent  of  the  1893  engine. 

3.  Decreased  cost  of  operation.     The  comparison  of  the  above 
mentioned  vessels  as  regards  relative  fuel  consumption  showed  that 
in  the  Atlantic  passenger  vessels  the  1913  vessel's  consumption  was 
94  per  cent  of  that  in  1893,  and  the  1913  cargo  boat  used  76 
per  cent  of  the  fuel  consumed  by  a  similar  vessel  in  1893. 

4.  Vibration  due  to  machinery  reduced. 

5.  Construction  and  operation  simplicity  attained,  reducing  de- 
lays and  cost  incident  to  repairs. 

6.  Lower  center  of  gravity  of  machinery,  resulting  in  increased 
headroom  above  the  machinery,  greater  stability  and  more  deeply 
immersed  propellers  which  are  not  so  often  "  racing  "  out  of  water. 

7.  Economy  of  space. 

8.  Reduction  of  friction  due  to  absence  of  sliding  parts. 

As  a  result  of  the  above  advantages  the  total  horse  power  of 
steam  turbines  applied  to  marine  propulsion  increased  from  prac- 
tically zero  in  1899,  to  25>°°o  in  1900;  35,000  in  1902;  75,000  in 
1903 ;  and  390,000  in  1906. 

The  latest  principal  developments  in  engines  have  been  con- 
nected with  overcoming  some  of  the  defects  of  the  turbine,  the 
most  vital  of  which  were* 


II4  MERCHANT  VESSELS 

1.  The  difficulty  in  reversing. 

2.  The  reduction  of  the  high  speed  of  the  rotating  parts  to  a 
speed  which  will  accommodate  itself  to  the  efficient  velocity  of 
the  propellers. 

The  original  turbine  could  not  be  run  astern  and  either  a  second 
turbine  or  some  kind  of  transformer  was  necessary.  The  blades 
of  the  second  turbine  are  placed  in  the  opposite  way,  so  that  when 
the  ship  is  going  ahead  they  revolve  idly.  The  turbine's  efficiency 
was  early  shown  at  high  speeds  and  this  continued  to  be  its 
strong  point.  It  was  impossible  to  impart  the  full  velocity  of  the 
revolving  turbine  shaft  to  the  propeller  shaft  of  a  vessel  not  de- 
signed to  make  high  speed;  the  water,  instead  of  being  used  for 
propulsion,  was  simply  churned  up  without  result.  Some  form  of 
reduction  was  therefore  necessary.  One  method  was  to  have  the 
turbine  drive  an  electric  dynamo,  the  current  of  which  would  oper- 
ate the  propeller  shafts  at  the  speed  desired.  This  also  solved 
the  problem  of  reverse  speed. 

The  advantages  of  the  electric  system,  briefly  stated,  are: 

1.  Economy  in  the  consumption  of  steam. 

2.  High  efficiency  at  low  speeds. 

3.  Reversibility  without  a  special  backing  engine  and  reverse 

power  nearly  100  per  cent  of  forward. 

4.  A  saving  in  weight  and  space. 

5.  Transmission  adaptable  to  any  power. 

6.  The  turbine  is  uninfluenced  by  the  racing  of  the  screws. 
Its  disadvantages  are : 

1.  The  complexity  of  the  necessary  accessories. 

2.  The  possible  effect  of  electricity  on  the  ship's  instrument, 

which  has  not  yet  been  demonstrated. 

3.  Difficulty  in  ventilating  generators  and  cooling  resistances, 

which  is  denied. 

Another  method  is  to  install  a  gear  wheel  transmission,  the 
speed  of  the  turbine  shaft  being  reduced  by  a  series  of  gear 
wheels  to  a  speed  appropriate  to  the  propeller  shaft.  The  loss 
of  power  is  small,  and  while  the  noise  is  augmented  the  vibration 
through  the  structure  of  the  ship  is  only  inappreciably  increased. 
Its  advantages  summarized  are : 

1.  A  reduction  in  weight  of  15  per  cent  over  the  directly  con- 

nected turbine. 

2.  Simplicity  of  mechanism. 


TYPES  OF  MARINE  ENGINES  115 

3.  Easier  repairs. 

4.  A  possible  speed  reduction  ratio  of  about  30  to  i. 
Its  disadvantages  are: 

1.  Some  noise,  though  slight. 

2.  Some  wear. 

3.  Nonreversibility. 

4.  Possible  limitation  of  power,  which  is  disputed. 
Hydraulic  transformer  gearing  is  also  used,  centrifugal  pump 

wheels  being  keyed  to  the  rotor  shaft  and  impulse-reaction  water 
turbine  wheels  similarly  secured  to  the  propeller  shaft.  The  water 
flows  from  the  pump  through  the  water  turbines  and  so  drives  the 
shaft  ahead  if  sent  through  one  set  and  astern  if  sent  through  the 
other.  Its  advantages  are : 

1.  No  limitation  as  to  power. 

2.  No  additional  noise  or  wear. 

3.  Saving  in  weight  compared  with  direct  turbines. 

4.  Reversibility  without  separate  turbines  and  backing  power 

equal  to  about  85  per  cent  of  forward. 
Its  disadvantages  are: 

1.  An  efficiency  of  about  89  per  cent  of  the  geared  turbine. 

2.  A  limitation  in  speed  reduction  to  a  ratio  of  about  6  to  i. 

3.  Complicated  mechanism. 

The  early  program  of  the  United  States  Emergency  Fleet 
Corporation  called  for  a  large  number  of  turbine-propelled  ves- 
sels. Due  to  the  difficulty  of  fitting  the  engines  to  the  vessels 
properly,  however,  and  to  the  lack  of  experienced  men  to  operate 
them,  the  program  was  later  revised  to  encourage  the  production 
of  reciprocating  engines.  This  was  generally  considered  to  be 
due  to  deficient  installation  and  handling  rather  than  to  inherent 
difficulties  with  the  turbine,  which  had  demonstrated  its  efficiency 
in  other  countries. 

For  the  propulsion  of  cargo  boats  where  the  speed  of  the  screw 
shafts  cannot  be  made  high  enough  to  admit  of  efficient  treat- 
ment in  the  turbine,  of  high-pressure  steam,  a  combination  of 
reciprocating  and  turbine  engines  has  been  adopted.  By  using 
a  cylinder  and  piston  for  the  high  pressure  and  a  turbine  for  the 
low  pressure,  the  turbine  becomes  available  for  slower  vessels 
where  otherwise  it  would  have  to  be  confined  to  vessels  of  over 
15  knots.  This  combination  was  first  adopted  in  the  Otaki,  a 
steamer  of  464  feet  length,  9900  tons  dead  weight.  A  compari- 


n6 


MERCHANT  VESSELS 


son  of  this  vessel  with  its  sister  ship  fitted  with  ordinary  twin- 
screw  quadruple-expansion  engines  showed  a  difference  in  steam 
consumption  per  effective  horse  power  of  20  per  cent  in  favor 
of  the  combination  engine.  The  latter  is  particularly  suitable  to 
vessels  of  fairly  large  power  and  moderate  speed  employed  on 
long  voyages.  The  disadvantages  are  increased  complexity  and 
cost  and  a  slight  increase  in  engine-room  weight,  but  increased 
economy  allows  a  reduction  in  boiler  capacity  and  in  boiler  room 
and  fuel  weights,  depending  on  the  length  of  the  voyage. 

The  following  table  x  will  show  the  effect  of  the  improvements 
previously  described  by  a  comparison  of  three  types  of  vessels  in 
1893  and  1913: 


Engines 

Boilers 

Relative 
Fuel 
Consumption 

Relative 
Machinery 
Weight 

i.  Atlantic  Passen- 
ger Ships 
1893 

1913 

Recipro- 
cating 
Turbine 

Cylindrical 
Water-tube 

IOO.O 

94.0 

IOO.O 

60.0 

2.  Intermediate 
Liners 
1893 

1913 

Recipro- 
cating 
Combina- 
tion recip  ' 
rocating 
and 
turbine 

Cylindrical 
Cylindrical 

IOO.O 

80.0 

IOO.O 

94.0 

3.  Cargo  Tramps 
1893 

1913 

Recipro-  • 
eating 
Turbine 

Cylindrical 
Cylindrical 

IOO.O 

76.0 

IOO.O 

84.4 

MARINE  BOILERS 

This  subject  naturally  divides  itself  into  two  parts,  (i)  the 
generation  of  heat  and  (2)  the  transmission  of  heat  or  generation 
of  steam.  For  the  generation  of  heat,  two  systems  of  firing  have 
been  employed:  the  natural  draft  and  the  artificial  draft,  either 

1  Adapted  from  Alexander  Gracie's  Twenty  Years'  Progress  in  Marine 
Construction,  Institute  of  Civil  Engineers,  cxciv,  London,  1914. 


TYPES  OF  MARINE  ENGINES 


117 


induced  or  forced  by  centrifugal  fans.  The  former  is  adaptable  to 
slow  freight  and  passenger  steamers  because  it  is  simpler  and 
economical  in  fuel  consumption,  while  the  latter  is  used  on  faster 
vessels  burning  over  20  pounds  of  coal  per  square  foot  of  grate 
area  per  hour. 

For  the  generation  of  steam,  two  types  of  boilers  are  in  use, 
the  cylindrical  and  water-tube.  A  cylindrical  boiler  with  three 
internal  corrugated  furnaces  and  return  tubes  is  now  quite  gen- 


Reproduced  by  permission  from  Bauer  &  Robertson,  "  Marine  Engines  and  Boilers," 
Crosby,   Lock-wood  &   Co.,  London 

FlG.   53. —  YARROW   BOILER 

erally  used  on  merchant  vessels.  The  advantages  of  this  boiler 
are  its  reliability  and  simplicity,  its  ability  to  stand  hard  usage, 
and  the  familiarity  of  engineers  with  it.  The  water-tube  boiler 
consists  of  a  number  o»f  tubes  surrounded  by  heat,  illustrated  by 
the  photograph  above  of  a  Yarrow  boiler. 

This  type  is  much  lighter  than  the  cylindrical  or  Scotch  boiler 
and  can  be  used  with  a  heavy  forced  draft.  With  the  cylindrical 
boiler  steam  cannot  be  raised  or  reduced  quickly  and  high  pres- 
sure cannot  be  used  in  boilers  of  great  capacity  because  the 
necessary  thickness  of  shell  makes  the  weight  excessive.  The 
water-tube  boiler  is  easier  to  repair  and  as  a  result  all  parts  are 


ii8  MERCHANT  VESSELS 

r 

likely  to  be  properly  repaired  and  renewed,  keeping  the  boiler  up 
to  par  while  as  the  cylindrical  boiler  deteriorates  the  working 
pressure  must  be  reduced  and  the  efficiency  sacrificed.  Acci- 
dents, furthermore,  are  more  serious  with  cylindrical  boilers  be- 
cause of  the  large  amount  of  water  contained.  But  the  water- 
tube  boiler  has  certain  disadvantages  which  partially  counterbal- 
ance the  advantages  enumerated,  namely: 

1.  More  affected  by  irregular  feeding. 

2.  More  affected  by  irregular  stoking. 

3.  Greater  susceptibility  to  fouling. 

4.  Difficulty  of  internal  cleaning. 

5.  Increased  complication  and  less  well-known. 

Thus,  cylindrical  boilers  maintain  their  popularity  with  all 
except  the  faster  vessels.  Among  the  more  popular  boilers  are 
the  Babcock  and  Wilcox,  Yarrow,  Niclausse,  Schulze,  Dur, 
Belleville,  Normand,  Thornycroft,  White,  Reid,  Seabury  and 
Almy. 

REFERENCES 

i.  GRACIE,  ALEXANDER:  "Twenty  Years'  Progress  in  Marine  Con- 
struction." Institution  of  Civil  Engineers,  London,  1914,  Vol. 
cxciv. 

2.  BAUER  AND  ROBERTSON  :  Marine  Engines  and  Boilers.  Crosby, 
Lockwood  &  Son,  London,  1905.  Part  I,  Sect,  iv;  Part  V, 
Sects,  ii  and  iv. 

3.  THOMAS,   C.   C:     Steam   Turbines.    Wiley  &   Sons,   New  York, 

1910.     Chaps.  VII,  VIII,  IX,  X. 

4.  New  International  Encyclopedia.    Article  on  "  Boilers." 

5.  McGiNNis,  A.  J. :     "  Advance  of  Marine  Engineering  in  the  Early 

Twentieth   Century."    Institute   of  Mechanical  Engineers  of 
United  Kingdom,  London,  July  29,  1909. 

6.  KIRKALDY,    A.    W. :    British    Shipping.     Kegan    Paul,    Trench, 

Trubner  &  Co.,  London;  Button  &  Co.,  New  York,  1914.     Chap. 
XIII. 


CHAPTER  VII 

OIL-BURNING  AND  INTERNAL-COMBUSTION  ENGINES 
IMPORTANCE  OF  OiC  AS  FUEL 

The  threatened  exhaustion  of  the  coal  supply  of  the  world  has 
been  referred  to  in  so  many  connections  that  it  is  now  generally 
accepted  as  a  very  real  possibility.  Whether  its  actual  disappear- 
ance is  an  impending  evil  or  not,  recent  years  have  exhibited  an 
increasing  tendency  for  the  demand  to  exceed  production,  with 
consequent  rising  price.  It  was  natural  for  persons  interested 
in  marine  propulsion  to  turn  their  attention,  therefore,  to  the  only 
other  great  fuel  available  —  oil.  It  is  extremely  significant  that 
the  present-day  prominent  fuel  subject  is  not  coal  but  oil,  indi- 
cating a  progression  from  an  "  age  of  coal "  to  an  "  age  of  oil." 
Rumors  are  circulated  of  possible  British  domination  of  the  oil 
supplies  of  the  world,  international  agreements  respecting  the 
Mesopotamian  fields  are  entered  into,  parliamentary  speeches  are 
made  indicating  oil's  importance  as  a  factor  in  the  merchant 
marine,  and  articles  are  written  on  the  oil  problem  in  the  United 
States.  Less  real  interest  is  manifested  in  the  transfer  of  coal 
from  Germany  to  France  than  in  who  shall  control  the  liquid 
fuel  supply.  The  automobile  has  been  a  potent  factor  in  condi- 
tions to  date ;  maritime  requirements  are  likely  to  play  an  equally 
important  part  in  the  future.  The  completed  program  of  the 
United  States  Shipping  Board  aggregates  about  10,000,000  dead- 
weight tons  and  of  this,  roughly  speaking,  one-fifth  consists  of 
coal-burning  vessels  and  four-fifths  of  oil-burners.  The  esti- 
mated fuel  oil  requirements  of  the  Shipping  Board  for  the  year 
1920  are  40,000,000  barrels  and  for  the  year  1921,  60,000,000 
barrels.  But  in  this  connection  the  statement  of  Admiral  W.  S. 

Benson,  Chairman  of  the  Shipping  Board,  is  most  significant. 

t 

If  we  are  forced  by  conditions  to  return  to  the  use  of  coal  for  our 
merchant  marine  we  might  as  well  give  up  the  problem.  Our  foreign 
competitors  are  using  every  means  so  completely  to  control  the  fuel 
oil  situation  that  in  the  very  near  future,  if  there  is  not  some  legisla- 

119 


120  MERCHANT  VESSELS 

tion  that  will  give  us  the  power  to  exert  certain  pressure  on  foreign 
interests,  they  will  be  able  to  keep  us  from  securing  the  oil  fuel  that 
we  must  have.  If  you  look  at  the  map  you  can  see  where  the  oil  is 
scattered  throughout  the  world.  Right  in  the  center  of  the  map  is 
Persia ;  there  is  one  of  the  biggest  oil  fields  in  the  world,  and  we  can- 
not get  any  of  that.  It  is  right  in  the  middle  of  our  trade  routes. 
Take  it  around  the  Caspian  Sea.  We  cannot  get  it  there.  Take  it 
in  India,  where  there  are  large  oil  wells,  take  it  in  Burma  and  other 
places.  The  oil  that  our  foreign  competitors  control  is  scattered 
around  the  world.  Ours  is  confined  to  our  own  country,  with  what 
we  are  getting  from  Mexico. 

Had  it  not  been  for  the  interference  of  the  war  with  the  devel- 
opment of  foreign  marine  engineering  oil  would  now  occupy  an 
even  more  important  position. 

Two  types  of  engines  dependent  upon  this  fuel  must  be  sharply 
distinguished:  the  oil-burning  engine,  which  except  as  regards 
fuel  may  be  identically  the  same  as  a  coal-burning  engine,  and 
the  internal-combustion  engine,  which  operates  on  a  principle  as 
distinct  from  the  steam  engine  as  a  typewriter  from  a  printing 
press. 

OIL-BURNING  ENGINES 

These  are  merely  steam  engines  equipped  with  burners  en- 
abling the  use  of  oil  as  fuel  instead  of  coal ;  in  fact,  a  coal-burn- 
ing engine  may  be  transformed  for  this  purpose  at  very  small 
expense  and  some  vessels  have  been  so  modified.  The  advantages 
derived,  therefore,  proceed  solely  from  the  substitution  of  fuels. 
Advantages  of  the  Oil-Burning  Engine: 

1.  The  most  obvious  advantage  of  oil  as  fuel  is  its  greater 
cleanliness^:     This  is  manifest  not  only  in  the  loading  but  in  the 
handling  of  the  fuel  after  it  is  on  board,  and  is  especially  advan- 
tageous in  connection  with  passenger  vessels.     Incidentally  this 
characteristic  results  in  time-saving,  for  stores  and  fuel  can  be 
simultaneously  taken  on  board  without  danger  of  contamination, 
and  the  vessel  can  be  cleaned  during  the  process. 

2.  At  one  time  oil  showed  a  saving  in  cost  as  compared  with 
coal,  but  its  price  has  rapidly  risen  within  the  last  few  years. 
Approximately  four  barrels  of  oil  are  usually  allowed  per  ton 
of  coal  and  the  question  of  economy  can,  therefore,  be  decided 
almost  by  the  application  of  arithmetic  to  current  prices.     In  some 


OIL-BURNING  ENGINES  121 

instances,  however,  it  has  been  found  that  vessels  whose  per- 
formances were  not  satisfactory  while  burning  coal  developed 
greater  efficiency  and  speed  on  oil,  which  introduces  an  indefinite 
factor  in  the  equation.  The  possibilities  of  oil  as  fuel  are  en^. 
hanced  in  importance  in  the  United  States  because  of  its  abun- 
dance here  and  the  possibility  of  American  control  of  the  product. 
The  United  States  produces  and  consumes  two-thirds  of  the  an- 
nual petroleum  output  in  the  world.  Conservation  of  American 
resources  and  acquisition  of  foreign  supplies  are  highly  important. 

3.  Another  advantage  of  the  oil-burner  is  the  simplicity  of  con- 
trol.     The  supply  of  fuel  to  the  burner  may  be  easily  regulated 
to  the  needs  of  the  moment  with  consequent  economy  and  ef- 
ficiency, while  the  efficient  production  of  energy  by  coal  depends 
upon  proper  firing. 

4.  Oil  may  be  easily  taken  on  board  at  small  cost.     Whereas 
a  large  force  of  men  was  required  for  coaling  a  good-sized  vessel, 
oil  is  easily  introduced  by  piping,  resulting  in  a  saving  of  both  labor 
and  time.     Thus  the  White  Star  liner  Olympic,  the  largest  British 
merchant  vessel  afloat,  is  enabled  by  substituting  oil  for  coal  to 
accomplish  a  round  trip  once  every  three  weeks,  inasmuch  as 
5000  gallons  of  oil  may  now  be  taken  on  in  eight  hours.     In  ad- 
dition, there  should  be  pointed  out  the  ease  of  transshipping  oil 
at  sea  through  a  hose,  enabling  the  replenishment  of  fuel  in  emer- 
gency.    This  is  of  particular  potential  advantage  to  war  vessels. 

5.  Oil  may  be  stowed  in  places  unsuitable  for  cargo,  whereas 
coal-bunker  space  reduces  the  carrying  capacity  of  the  vessel. 
Double-bottom  tanks  are  the  most  common  reservoir  for  oil  fuel, 
and  other  space  formerly  used  for  fuel  becomes  earning  space. 
Since  bulky  products  form  a  considerable  part  of  United  States' 
exports  this  is  especially  important  to  us.     It  should  also  be  noted 
that  oil  preserves  the  metal  of  the  compartments  where  it  is  stored, 
whereas  coal  bunkers  demand  frequent  scaling  and  painting  to 
prevent  deterioration.     The  additional  cargo-carrying  space  made 
available  by  oil  fuel  is  frequently  overestimated,  however,  by  not 
considering  that  the  space  otherwise  occupied  by  coal  bunkers 
is  an  inconvenient  or  undesirable  portion  of  the  vessel  for  cargo. 

6.  Besides  the  economy  effected  by  utilizing  the  double-bottom 
tanks   as    fuel   reservoirs   and   releasing   other   space   for  cargo, 
there  is  the  actual  reduction  in  the  amount  of  space  occupied  by  the 
fuel.     The  space  required  for  engines  and  boilers  is  the  same  as 


122  MERCHANT  VESSELS 

demanded  on  the  coal-burner,  the  machinery  being  the  same,  but 
the  space  required  for  the  oil  fuel  is  only  from  50  to  60  per  cent 
of  the  space  demanded  by  an  equivalent  amount  of  coal.  There 
is  some  reduction  possible  also  in  fire-room  space,  because  less 
room  is  required  for  stoking  oil-fed  engines. 

7.  A  very  important  corollary  of  the  above  is  the  resultant 
ability  of  the  vessel  to  carry  more  fuel  on  a  voyage  and  reduce 
the  number  of  stops.     In  other  words,  either  the  steaming  radius 
of  the  vessel  is  considerably  increased  or  the  possible  speed  is 
augmented.     For  example,  fast  travel  between  Europe  and  the 
Antipodes  has  been  hitherto  restricted  because  of  the  inability  to 
carry  enough  fuel  to  maintain  the  desired  speed ;  oil  obviates  this 
difficulty.     With  a  supply  of  reserve  fuel,  furthermore,  the  vessel 
is  given  some  option  as  to  where  purchases  shall  be  made  and  can 
buy  oil  where  it  is  cheapest,  but  for  the  coal-burning  vessel  cer- 
tain coaling  ports  on  given  voyages  were  necessities.     The  lack 
of  bunkering  facilities  in  foreign  waters  also  placed  this  country 
under  obligations  to  foreign  nations. 

8.  The  cost,  delay,  and  waste  of  starting  and  hauling  the  fires  of 
coal-burners  is  largely  eliminated. 

9.  The  working  force  required  is  greatly  reduced  by  dispens- 
ing with  nearly  all  the  firemen  and  eliminating  coal  passers.     The 
higher  wages  paid  on  American  vessels  made  this  an  important 
factor. 

10.  The  oil-burning  vessel  derives  an  advantage  also  from  cur- 
rent measurement  rules.     Under  the  Danube  rule  the  fuel  space 
is  estimated  to  be  a  percentage  of  the  engine  space  and  if  theoreti- 
cally coal  would  require  50  per  cent  of  the  engine  space  oil  as 
fuel  would  require  only  25  per  cent  of  such  space.     Nevertheless, 
the  deduction  from  gross  tonnage  for  propelling  power  would  be 
the  same — il/2  times  the  engine  space.     Under  the  percentage 
rule  the  oil-burner  also  benefits.     The  deduction  is  32  per  cent  of 
the  gross  tonnage  of  the  vessel  and  this  gross  tonnage  (and  conse- 
quently the  deduction)  is  increased  by  the  oil  carried  in  double- 
bottom  tanks.     Along  with  the  greater  deduction,  however,  goes 
a  smaller  amount  of  space  actually  utilized  for  fuel  and  as  a  re- 
sult the  ratio  of  cargo  capacity  to  net  tonnage  is  increased. 

Eight  years  ago  at  the  London  Oil  Congress  a  speaker  showed 
the  resultant  economies  from  the  substitution  of  oil  for  coal  on  the 
transatlantic  liner  Mauretania.  This  vessel  consumes  about  600 


OIL-BURNING  ENGINES  123 

tons  of  coal  per  day,  fed  by  hand  at  the  rate  of  25  tons  per  hour, 
so  that  a  round  trip  requires  a  provision  of  about  11,000  tons. 
By  the  use  of  oil  about  3300  tons  of  liquid  fuel  would  be  sub- 
stituted for  the  coal,  all  of  which  could  be  carried  in  double- 
bottom  tanks  and  the  space  otherwise  occupied  released  for  cargo. 
Assuming  that  $5  a  ton  could  be  earned  on  cargo  the  receipts 
would  be  increased  by  at  least  $30,000.  But  in  addition,  by 
mechanical  firing  the  stokejooW  force  could  be  reduced  from  312 
to  30  men,  a  force  adequate  to  attend  to  the  oil-burners  and 
regulate  the  feed  water,  releasing  space  for  about  200  third-class 
passengers.  At  $25  per  head  this  would  add  $5000  to  the  income. 
Furthermore,  with  coal  firing  it  is  necessary  to  draw  about  32  of 
the  192  furnaces  every  watch  to  remove  clinker  and  for  general 
cleaning,  so  that  the  aggregate  energy  is  reduced  from  68,000 
horse  power  to  58,000  horse  power.  By  oil  the  steam-raising 
capacity  would  thus  be  increased  over  15  per  cent,  which  would 
save  8  or  10  hours  in  the  voyage.  At  present  a  large  force  is 
required  to  bunker  the  coal,  and  20  hours  of  time  are  consumed 
in  the  process,  while  with  oil  the  fuel  required  can  be  taken  on  in 
6  or  8  hours  without  dust  or  noise.  This  excellent  forecast  of  the 
benefits  of  oil  has  recently  been  strikingly  verified  by  the  Cunard 
liner  Aqultania  covering  the  last  129  miles  of  a  voyage  at  a  speed 
of  27.4  knots,  which  exceeds  the  best  previous  record  by  over  one 
knot  per  hour,  and  the  reduction  of  the  schedule  of  the  Olympic 
to  one  round  trip  every  three  weeks.  The  Aquitania's  perform- 
ances with  coal  fuel  had  never  come  up  to  the  builder's  ex- 
pectations and  the  reduction  of  the  Olympic's  schedule  would  have 
been  impossible  with  the  fuel  previously  used. 

Disadvantages  of  Oil  Fuel : 

1.  While  its  cost  is  from  two  to  five  times  that  of  coal  it  is  less 
than  50  per  cent  more  efficient.     The  factor  of  cost  will,  there- 
fore, be  an  important  influence  in  its  use. 

2.  While  coaling  stations  have  been  built  to  supply  the  needs 
of  commerce,  it  will  be  some  time  before  supplies  of  oil  are  sit- 
uated so  as  adequately  to  meet  the  needs  of  ocean  vessels.     It  was 
necessary  for  the  Shipping  Board  to  establish  additional  stations 
during  the  war  in  the  United  States  in  order  properly  to  supply 
the  oil-burning  vessels  in  use,  and  the  Director  of  Operations  of 
the  Shipping  Board  now  states  that  the  volume  of  fuel  oil  earlier 


124  MERCHANT  VESSELS 

referred  to  must  be  produced  and  transported  in  special  carriers  to 
select  places  around  the  world,  failing  in  which  our  ships  become 
as  useless  as  "  painted  ships  upon  a  painted  ocean." 

3.  The  substitution  of  oil  for  coal  merely  affects  the  fuel  and 
not  the  mechanism  through  which  this  is  translated  into  energy, 
whereas  internal-combustion  engines  utilize  new  mechanical  prin- 
ciples as  well  as  the  advantages  of  the  material. 

INTERNAL-COMBUSTION  GAS  ENGINES 

These  may  be  divided,  with  reference  to  the  fuel  used,  into 
two  classes:  (i)  engines  operated  with  gasified  gasoline,  naphtha, 
kerosene,  or  other  light  refined  oils ;  (2)  enginel  operated  with  pro- 
ducer gas. 

The  former  group  may  be  dismissed  from  consideration  as  be- 
ing familiar  to  all  and  suitable  at  present  only  for  small  boats, 
where  the  cost  can  be  ignored  in  view  of  the  elimination  of  the 
cumbersome  steam  plant. 

Producer-Gas  Engines. — The  principal  parts  of  the  engine  are 
the  producer,  the  scrubber,  the  drier,  and  the  cylinders.  Pro- 
ducer gas  is  the  gas  obtained  by  the  partial  combustion  of  fuel, 
usually  coal,  in  a  gas  producer,  a  current  of  air  mixed  with  steam 
or  water  vapor  being  passed  through  a  deep  bed  of  fuel  in  a 
closed  producer.  After  burning  is  once  started  in  the  producer 
the  air  current  serves  to  keep  the  process  of  combustion  contin- 
uous. Producers  are  generally  classified  in  two  groups.  In  suc- 
tion producers  the  draft  through  the  producer  is  created  by  the 
suction  of  the  engine.  In  pressure  produCers-the  draft  is  created 
by  some  form  of  blower,  which  raises  the  pressure  at  the  entering 
side  or  end  of  the  fuel  column.  The  gas  driven  off  by  the  pro- 
ducer is  passed  through  the  scrubber,  where  it  is~cooled  and  puri- 
fied and  thence  to  the  drier,  where  it  is  dried  and  fed  to  the  cylin- 
ders of  the  engine. 

The  gas  is  consumed  in  the  cylinder,  as  in  the  Diesel  oil  engine, 
described  later,  but  by  reason  of  its  gaseous  form  this  consumption 
takes  the  form  of  an  explosion.  The  ignition  producing  the  ex- 
plosion is  supplied  by  an  electric  spark  or  a  hot  bulb  in  the  cylin- 
der. The  cylinders  of  the  producer-gas  engine  are  larger  than 
those  required  for  gasoline.  The  engine  may  be  of  either  the 
four-cycle  or  two-cycle  type. 


OIL-BURNING  ENGINES  125 

Advantages  of  the  Producer-Gas  Engine: 

1.  Its  chief  merit  is  the  economy  with  which  it  is  claimed  the 
gas  can  be  produced,  since  all  grades  of  coal  and  even  peat  may 
be.  used  as  fuel.     On  the  other  hand,  it  is  claimed  that  the  best 
results   are   obtained   only    with   anthracite   and   the   advantage 
in  cost  consequently  considerably  dwindles. 

2.  A  reduction  in  the  amount  of  coal  consumed  as  compared 
with  the  coal-burning  vessel. 

3.  A  reduction  in  the  amount  of  space  required  for  fuel  as  com- 
pared with  the  steamer,  although  it  shows  no  saving  as  compared 
with  the  internal-combustion  oil  engine. 

4.  It  requires  less  space  than  the  steam  engine  because  the  space 
required  for  the  producer  is  only  about  one-third  that  necessary 
for  a  water-tube  boiler  and  one-eighth  that  required  for  a  Scotch 
boiler. 

5.  Some  reduction  is  accomplished  in  the  number  of  attendants 
required  as  compared  with  the  coal-burning  ship. 

Disadvantages  of  the  Producer-Gas  Engine: 

1.  The  economy  in  fuel  is  considerably  reduced  if  anthracite 
or  other  expensive  coal  is  required  to  obtain  the  best  results. 
Greater  economy  is  obtained  from  the  Diesel  engine  if  the  price  of 
oil  does  not  rise  too  high. 

2.  No  saving  in  the  weight  or  space  required  by  the  engine  is 
obtained,  whereas  the  internal-combustion  oil  engine  furnishes  a 
considerable  saving.     A  much  greater  saving  in  cargo  space  and 
consequent  increase  in  earning  capacity  is  possible  with  the  latter. 

3.  By  reason  of  the  gas  producer  required  a  greater  crew  is 
necessary  than  for  the  operation  of  an  equally  powerful  Diesel 
engine. 

4.  Greater  difficulty  has  been  encountered  in  reversing  the  gas 
engine  than  the  Diesel  engine  and  this  was  one  of  the  principal 
problems  of  the  latter  type. 

THE  INTERNAL-COMBUSTION  OIL  ENGINE 

Of  these  the  Diesel  and  a  group  of  engines  known  as  semi- 
Diesel  engines  are  most  used.  Dr.  Rudolf  Diesel,  a  German  en- 
gineer, after  experimenting  a  number  of  years  completed  an  ex- 
perimental engine  in  1893.  A  patent  was  granted  him  in  the 


126  MERCHANT  VESSELS 

United  States  in  1895,  and  up  to  1902  the  principle  was  applied 
solely  to  stationary  engines,  many  of  which  were  in  successful 
operation..  About  1908  the  first  large  Diesel  marine  engine  was 
installed  to  convert  a  large  passenger  steamer  on  Lake  Zurich, 
Switzerland,  into  an  internal-combustion  vessel,  and  about  1910  the 
first  ocean-going  vessel  of  any  size  was  so  equipped  —  the  Vul- 
canus.  This  is  a  looo-ton  Dutch  tank  ship  fitted  with  a  450 
horse  power  engine.  In  1911  there  were  365  vessels  equipped 
with  Diesel  marine  engines  and  since  that  time  the  number  has 
increased  much  more  rapidly,  but  figures  of  the  extent  of  present 
use  are  difficult  to  secure. 

Operation  of  the  Diesel  Engine. —  Using  the  four-stroke 
cycle  as  an  illustration,  the  operation  of  the  Diesel  engine  may  be 
described  as  follows : 

A  suction  stroke  draws  a  supply  of  air  into  the  cylinder  and  by 
a  compression  stroke  of  the  piston  this  air  is  compressed  with  a 
consequent  rise  in  temperature  sufficient  to  ignite  a  gaseous  vapor 
were  one  present.  At  the  end  of  this  compression  stroke,  by  which 
the  pressure  has  been  increased  to  about  500  pounds  per  square 
inch,  oil  is  sprayed  into  the  cylinder.  Since  this  injection  must 
take  place  at  a  higher  pressure  than  that  obtaining  in  the  cylinder 
it  is  performed  by  an  air  blast  fed  from  a  small  reservoir  charged 
to  a  pressure  of  750  pounds.  An  air  compressor  is  necessary  to 
start  the  engine.  The  introduction  of  the  fuel  might  be  compared 
to  the  spraying  of  a  solution  by  an  atomizer  and  the  high  temper- 
ature in  the  cylinder  causes  immediate  combustion,  resulting  in  a 
power  stroke.  The  fourth  period  in  the  cycle  expels  the  burned 
gases.  The  maximum  temperature  within  the  cylinder  is  about 
2500  degrees  Fahrenheit,  but  since  no  metal  now  known  would 
withstand  such  heat  the  parts  subjected  to  it  are  surrounded  by  a 
water  jacket  for  cooling  purposes.  The  work  performed  by  the 
engine  may  be  regulated  by  changing  either  the  quality  or  quan- 
tity of  the  mixture  injected  into  the  cylinder  or  by  a  combina- 
tion of  these  methods.  The  former  is  usually  employed  in  the 
Diesel-type  engine.  The  ignition  in  the  straight  Diesel  engine  is 
the  result  of  the  high  compression  of  air.  A  hot  tube  in  the  cylin- 
der, supplied  with  heat  from  an  outside  source,  an  electric  spark 
or  a  hot  bulb  of  cast  iron  in  the  cylinder  would  produce  similar 
results,  the  latter  being  sometimes  spoken  of  as  a  semi-Diesel  en- 
gine. It  is  evident  that  the  internal-combustion  engine  decidedly 


OIL-BURNING  ENGINES  127 

differs  from  the  steam  engine,  whether  the  latter  operates  with 
coal  or  oil  as  fuel.  In  the  steam  engine  the  energy  is  received 
by  the  engine  ready-made;  in  the  internal-combustion  engine  the 
engine  must  produce  its  own  energy.  In  the  steam  engine  the  com- 
bustion takes  place  in  the  furnace  and  the  results  are  transmitted 
to  the  cylinders ;  in  the  internal-combustion  engine  the  combustion 
takes  place  in  the  cylinder  itself.  The  internal-combustion  oil 
engine  consumes  liquid  fuel  while  the  internal-combustion  gas 
engine  requires  gaseous  fuel. 

Several  different  methods  have  been  adopted  for  reversing  the 
direction  of  the  screw  propeller  relatively  to  the  engine,  among 
them  the  following : 

1.  In  small  vessels  to  turn  the  screw  propeller  itself  on  the 
hub,  thus  temporarily  converting  a  propelleT~wifn  a  right-hand 
pitch  to  one  with  a  left-hand  pitch  or  vice  versa. 

2.  To  use  a  propeller  shaft  which  is  detached  from  the  crank 
shaft  of  the  engine.     Both  shafts  are  in  the  same  straight  line 
but  the  actual  physical  connection  is  macle  by  a  clutch  and  gearing. 

3.  To  join  the  propeller  shaft  and  engine  shaft  and  change  the 
rotation  of  the  engine  as  a  whole  by  manipulating  the  engine  for 
the  moment  by  an  independent  supply  of  compressed  air  or  by 
premature  ignition -and  combustion. 

Both  four-stroke  cycle  and  two-stroke  cycle  Diesel  engines  are 
used  for  marine  work.  In  the  four-stroke  cycle  there  are  a  suc- 
tion stroke,  a  compression  stroke,  a  power  stroke,  and  an  exhaust 
stroke.  On  the  suction  stroke  a  supply  of  gas  and  air  is  taken 
into  the  cylinder  through  an  inlet  valve.  On  the  compression 
stroke  the  intake  of  mixture  ceases,  the  charge  in  the  cylinder  is 
compressed  and  at  the  end  of  the  stroke  ignition  occurs.  On  the 
power  stroke  the  temperature  and  pressure  of  the  gas  increase 
suddenly,  due  to  combustion,  drive  the  piston  out  and  return  to 
original  conditions.  On  the  exhaust  stroke  the  refuse  of  the 
burned  gases  is  expelled.  In  the  two-stroke  cycle  there  are  a 
working  or  expansion  stroke  and  a  charge^  or  compression  stroke. 
Th^first  stroke  compresses  the  air  which  has  been  forced  into  the 
cylinder  by  a  scavenge  pump.  Fuel  is  injected,  combustion  takes 
place,  and  the  working  stroke  follows.  During  the  second  stroke 
the  scavenge  pump  expels  the  burned  gases  through  the  exhaust 
and  refills  the  cylinder  with  fresh  air.  Both  types  have  their  ad- 
herents, both  are  being  experimented  with,  and  both  have  their 


128  MERCHANT  VESSELS 

advantages  and  disadvantages.  The  four-stroke  cycle  develops 
high  speed  at  low  cost,  especially  for  small  engines  and,  in  addition, 
is  of  simpler  construction.  Its  disadvantages  are  said  to  be  a  vary- 
ing torsional  movement,  heavy  flywheel,  small  specific  output, 
large  dimensions  and  the  contamination  of  the  new  charge  by 
burned  gases.  It  is  claimed  for  the  two-stroke  cycle  that  its  spe- 
cific output  is  larger  than  that  of  the  four-cycle,  that  the  size  of  the 
engine  is  only  one-half  that  of  the  four-cycle  for  the  same  output, 
the  elimination  of  valves  by  ports  in  the  cylinder  walls,  more 
uniform  torsional  movement  and  ease  of  reversibility.  It  is 
admitted,  however,  that  this  type  has  greater  frictional  resistance 
and  lower  mechanical  efficiency,  lower  speed,  larger  heat  losses 
during  the  power  stroke  and  complications  in  scavenging. 
Advantages  of  the  Internal-Combustion  Oil  Engine: 

1.  We  have  previously  mentioned  the  greater  steaming  radius 
attained  by  steamers  on  oil  fuel.     With  the  greater  engine  ef- 
ficiency supplied  by  the  Diesel  principle  this  radius  is  still  further 
increased.     The  tanks  of  large  vessels  will  give  a  cruising  radius 
of  25,000  miles,  sufficient  to  go  around  the  world,  passing  all  fuel 
stations.     One  vessel  is  said  to  have  attained  three  times  its  former 
cruising  radius  with  the  same  bunker  capacity  as  for  coal. 

2.  The  advantages  of  oil  as  fuel  previously  mentioned  are,  of 
course,  all  present  in  the  Diesel  engine,  including  the  cleanliness, 
the  facility  of  fueling  and  transshipping  fuel,  the  preservation  of 
fuel  compartments,  and  the  saving  in  labor  and  time  in  taking  on 
fuel. 

3.  Diesel  engines  develop  power  at  less  cost  when  oil  does  not 
cost  more  than  three  or  four  times  as  much  by  weight  as  coal,  due 
to  the  fact  that  the  weight  of  fuel  required  is  approximately  only 
one-fifth  of  that  required  for  a  steam  plant  of  equal  power.     Ref- 
erence is  made  later  to  the  saving  in  weight  and  volume  of  fuel. 

4.  Economy  in  space  is  effected  in  two  directions:  engine  and 
fuel.     The  saving  in  engine  space  is  the  result  of  the  elimination 
of  boilers,  light  and  air  shafts  leading  to  the  boiler  rooms,  and 
the  smoke  funnels.     The  saving  in  space  may  be  roughly  estimated 
at  from  20  to  33  per  cent  of  the  space  required  for  steam  engines. 
In  particular  vessels  a  saving  of  as  high  as  50  per  cent  has  been 
claimed.     In  this  connection  it  should  be  remembered  that  the 
measurement  rules  offer  no  incentive  for  reducing  the  engine-room 


OIL-BURNING  ENGINES  129 

space  below  a  given  proportion  of  the  gross  tonnage  because  of 
the  system  under  which  deductions  are  allowed  —  this  is  fully 
discussed  in  the  section  on  measurement.  As  regards  fuel,  not 
only  is  less  storage  space  required  for  oil,  ton  for  ton,  but  double- 
bottom  tanks  are  available  for  storage,  releasing  portions  of  the 
vessel  for  other  purposes.  In  general,  it  may  be  said  that  the  oil 
occupies  only  from  20  to  30  per  cent  of  the  space  required  for  an 
equivalent  amount  of  coal.  In  the  first  large  vessel  equipped  with 
Diesel  engines,  a  passenger  steamer  on  a  Swiss  lake,  the  fuel- 
carrying  capacity  was  said  to  be  increased  tenfold.  This  saving 
in  fuel  space  required  is  one  of  the  greatest  economies  of  the  Diesel 
engine. 

5.  Economy  in  weight;  here  again  a  saving  is  effected  in  both 
engines  and  fuel.     The  average  saving  in  weight  due  to  the  engine 
is  100  tons.     One  writer  states  that  the  "  approximate  saving  in 
weight  for  a   1500  shaft  horse  power  installation    (slow-speed 
Diesel  engine  of  ordinary  type  adapted  for  cargo  vessels)  is  some- 
where in  the  neighborhood  of  150  tons  in  favor  of  the  Diesel  en- 
gine as  compared  with  the  steam  equipment,  and  approximately  the 
same  ratio  applies  for  larger  powers."     As  regards  fuel  there  is  a 
possibility  of  saving  from  70  to  80  per  cent  in  weight,     Of  two 
similar  British  cargo  vessels  it  was  found  that  one  gained  200 
tons  because  of  the  saving  in  weight  of  fuel  when  equipped  with 
Diesel  engines.     A  vessel  of  2500  to  3500  tons  displacement  pro- 
pelled by  a  steam  engine  of  noo  or  1200  indicated  horse  power 
would  require  15  tons  of  coal  per  day,  while  a  Diesel  engine  would 
require  only  4  tons  of  oil.     If  the  vessel  bunkered  for  20  days  this 
would  mean  a  saving  of  220  tons.     Allowing  for  the  placing  of  oil 
in  less  accessible  places  there  would  be  an  additional  saving  in 
cargo  space.     In  the  pioneer  Diesel -engined  lake  steamer  referred 
to  above  there  was  a  saving  of  33  per  cent  in  weight  with  an  in- 
creased speed.     This  is  especially  important  for  dead-weight  car- 
riers where  displacement  is  of  primary  importance. 

6.  Naturally,  as  a  consequence  of  the  savings  referred  to  above, 
there  result  (i)  an  increased  dead-weight  capacity,   (2)  an  in- 
creased space  for  cargo ;  or  in  other  words,  an  increased  potential 
earning  power  for  the  vessel.     The  net  saving  effected  depends 
upon  the  construction  of  the  vessel  and  the  effect  of  measurement 
rules.     One  writer  states  that  an  extra  cargo  can  be  carried  equal 
to  about  15  per  cent  of  the  displacement  of  the  vessel.     In  the 


130  MERCHANT  VESSELS 

Jutlandia,  of  5000  tons  displacement,  a  gain  of  20  per  cent  in 
freight  and  passenger  space  resulted  from  Diesel  engines;  in  the 
Seelandia,  of  10,000  tons  displacement,  a  gain  of  1000  tons  of 
cargo  was  obtained.  A  cargo  vessel  of  5550  tons  fitted  with 
Diesel  engines  was  found  to  have  an  extra  freight-carrying  capacity 
of  280  tons  as  compared  with  a  sister  ship  fitted  with  steam  en- 
gines. It  is  probable  that  10  per  cent  increase  in  freight-carrying 
ability  is  a  conservative  estimate.  In  a  7ooo-ton  vessel  it  was 
reported  that  the  gain  was  as  high  as  800  tons. 

7.  In  connection  with  the  actual  increase  in  cargo-carrying  ca- 
pacity described  above  it  must  be  pointed  out  that  the  Diesel- 
engined  vessel  derives  a  very  great  advantage  from  the  meas- 
urement rules  and  consequently  in  the  payment  of  dues  and  taxes 
which  are  levied  on  the  basis  thereof.     The  same  rules  are  applied 
in  deducting  the  engine  and  fuel  space  from  the  gross  tonnage 
as  for  steamers,  whereas  the  space  actually  occupied  is  much  less 
and  the  carrying  capacity  is  much  greater.     This  will  be  more  fully 
appreciated  after  examining  Part  II  of  this  volume. 

8.  The  safety  of  the  vessel,  crew  and  cargo  is  increased  by  the 
Diesel  engine  through  the  elimination  of  stored-up  energy  which 
might  inflict  damage  by  explosion. 

9.  The  Diesel  engine  is  not  subject  to  the  disadvantages  inci- 
dental to  the  necessity  for  an  adequate  and  satisfactory  water 
supply. 

10.  The  internal-combustion  engine  is  ready  to  start  without  the 
steam  engine's  delay  in  getting  up  pressure  and  the  expenses  of 
operation  stop  when  the  engine  stops.     No  useless  energy  is  con- 
sumed in  keeping  up  fires  and  no  potential  power  is  lost  by  fur- 
naces being  cleaned. 

11.  A  higher  thermodynamic  efficiency  is  developed  by  the  Diesel 
engine,  sometimes  as  great  as  30  per  cent. 

12.  Another  very  important  saving  with  the  Diesel  engine  is  in 
labor  cost.     This  economy  is  obtained  by  the  absence  of  boilers, 
condensers,  and  other  accessories  in  a  steam  plant  which  require 
attention.     The  labor-saving  in  the  case  of  the  Mauretania  by 
the  substitution  of  oil  for  coal  will  be  remembered.     The  following 
table  is  given  as  an  illustration  of  the  saving  by  the  Diesel  engine 
in  the  case  of  a  Pacific  Coast  vessel  425  feet  long,  carrying  10,000 
tons  of  cargo  on  a  voyage  from  San  Francisco  to  Australia  and 
return.  .  There  is,  therefore,  in  the  Diesel  engine  vessel  as  com- 


OIL-BURNING  ENGINES 


pared  with  the  oil-burner,  a  saving  of  five  men,  their  subsistence, 
their  quarters,  the  care  of  their  linen,  and  the  additional  help  in 
the  steward's  department,  or  approximately  $600  per  month.  To 
take  a  smaller  vessel  as  an  illustration,  the  motor  ship  Apex, 
operated  between  Puget  Sound  and  Alaska,  carrying  cannery  sup- 
plies and  fish,  carried  only  3  engineers  and  3  oilers  with  no  fire- 
men and  no  bunker  men  or  wipers,  as  compared  with  a  steam 
vessel  similarly  employed,  which  used  seven  additional  men.  This 
was  a  saving  of  approximately  $700  per  month  in  wages,  and  in- 
cidentally this  vessel  carried  275  tons  more  cargo  and  saved  $2400 
a  month  in  fuel  and  oil  as  compared  with  the  steam  vessel  similarly 
engaged. 

CREW  REQUIRED 


For 
Diesel  engine 

For 
Oil-burning  steam 
engine 

For 
Coal-burning  steam 
engine 

i  chief  engineer 
3  assistant  engineers 
3  oilers 
3  wipers 
i  storekeeper 
i  machinist 

i  chief  engineer 
3  assistant  engineers 
3  oilers 
3  wipers 
i  storekeeper 

i  chief  engineer 
3  assistant  engineers 
3  oilers 
3  wipers 
i  storekeeper 

i  electrician 

3  firemen 

Q  firemen 

i  deck  engineer 

i  deck  engineer 

3  water  tenders 

^  water  tenders 

"?  coal  passers 

Total  13 

Total  1  8 

Total  27 

13.  The  Diesel  engine  has  also  proved  useful  as  an  auxiliary 
engine  in  sailing  vessels.  One  writer  believes  that  it  will  pro- 
long to  some  extent  the  existence  of  the  large  sailing  ship.  As  a 
cheap  method  of  conveying  freight  long  distances  the  sailing  ves- 
sel is  undoubtedly  valuable,  but  the  great  disadvantages  attending 
its  employment  are  the  liability  of  becoming  becalmed  for  days  or 
even  weeks,  and  the  absence  of  reserve  power  at  critical  moments. 
With  the  auxiliary  power,  however,  it  is  possible  to  make  upwards 
of  4  miles  per  hour  during  the  absence  of  wind  and  escape  the 
calm  zone. 

In  order  to  present  the  situation  impartially  the  disadvantages 
of  the  Diesel  engine  are  briefly  presented : 


i32  MERCHANT  VESSELS 

1.  The  motor  has  to  be  started  by  an  outside  agency  and  auxil- 
iary power  must  be  accumulated  from  a  previous  running  of  the 
engine. 

2.  Hitherto  the  problem  of  reversing  has  been  a  serious  one, 
and  in  some  cases  gearing  must  be  introduced  in  the  transmission 
machinery  between  the  motor  and  its,  work. 

3.  It  is  most  efficient  at  only  one  speed  and  to  meet  lower  speeds 
must  be  geared  down  in  order  to  secure  power. 

4.  In  the  four-stroke  cycle  variety,  there  is  but  one  power 
stroke  in  four  piston  strokes.     Therefore,  to  secure  uniformity  in 
turning  effort  for  each  movement  of  the  piston  the  number  of 
cylinders  has  to  be  increased. 

5.  Upon  interruption  of  the  fuel  supply  or  the  ignition  the  en- 
gine stops  short  without  warning. 

6.  Lack  of  familiarity  by  engineer's  with  the  engines  renders 
it  more  difficult  to  get  a  satisfactory  crew. 

7.  The  initial  cost  of  installation  has  been  greater  than  for 
steam  engines,  including  the  boilers. 

8.  Oil  supplies  are  not  so  satisfactorily  distributed  over  the 
world  as  coaling  stations. 

Fuel  for  Diesel  Engine. —  It  is  hardly  an  exaggeration  to  say 
that  any  kind  of  oil  may  be  used  in  the  Diesel  engine.  The  only 
qualification  is  that  for  t-ar  oils  a  special  arrangement  is  necessary. 
The  list  of  available  fuels  includes  crude  petroleum,  residual  min- 
eral oils  remaining  after  lighter  oils  have  been  distilled,  tar  or 
creosote  oils,  gasoline  or  petrol,  naphtha,  kerosene,  alcohol,  vege- 
table oils,  and  animal  oils.  Of  these  the  first  three  kinds  are  pre- 
eminently important.  Gasoline,  naphtha  and  kerosene  are  too 
dangerous  and  too  expensive  for  use  in  any  except  small  boats 
where  their  convenience  is  -an  important  consideration.  Alcohol, 
vegetable  oil,  and  animal  oils  are  insufficient  in  supply,  nonuniform 
in  quality  or  dangerous.  Crude  oil  and  residual  mineral  oils  are 
most  used  at  the  present  time.  Crude  oil  would  be  used  to  a 
greater  extent  were  it  not  for  the  high  value  of  the  lighter  oils 
which  may  be  separated  from  it  and  the  fact  that  the  presence  of 
volatile  oils  renders  storage  more  dangerous.  Tar  or  creosote  oils, 
obtained  by  the  distillation  of  coal  or  crude  oil,  are  beginning 
to  be  rather  extensively  used,  particularly  in  Germany,  and  may 
become  a  factor  of  considerable  importance,  though  it  is  likely  that 
crude  and  residual  oils  will  retain  first  place. 


OIL-BURNING  ENGINES  133 

Semi-Diesel  Engines. —  This  name  has  been  applied  to  engines 
constructed  on  principles  slightly  different  from  the  Diesel  engine. 
These  are,  in  general,  a  compromise  between  the  oil  engine  and 
the  gas  engine.  Such  vaporizer  oil  engines  obtain  their  power 
by  the  combustion  of  oil  vapor  in  the  cylinder,  as  in  the  Diesel 
engine,  but  obtain  ignition  by  an  electric  spark  or  a  hot  bulb  and 


Courtesy  of  H.  Lund  &r  Co.,  San  Francisco 
FlG.    54. —  SEMI-DIESEL  ENGINE 

not  by  air  compression  alone.  They  differ  from  the  Diesel  en- 
gine in  that  they  vaporize  the  oil,  and  from  the  gas  engine  in  that 
they  depend  upon  combustion  and  not  explosion.  They  are 
claimed  to  produce  perfect  combustion,  have  a  smaller  initial  cost, 
do  not  require  expensive  air  compressors,  and  have  a  working 
pressure  about  one-third  that  of  a  Diesel  engine.  The  engine  is 
also  claimed  to  be  more  flexible,  the  power  not  decreasing  so 
rapidly  when  the  engine  is  brought  to  reduced  speed  by  an  over- 
load. The  alleged  disadvantages  are  higher  fuel  consumption  and 
lower  efficiency.  Various  types  of  semi-Diesel  engines  are  pro- 
duced by  different  manufacturers  and  an  illustration  of  one  type  of 
such  an  engine  is  reproduced  above : 


134  MERCHANT  VESSELS 


REFERENCES 

1.  JOHNSON,  E.  R. :    Report  on  Measurement  of  Vessels  for  the 

Panama  Canal.  Washington,  1913.  Chap.  X.  (Brief  descrip- 
tion of  the  operation  of  internal-combustion  engines  and  excel- 
lent discussion  of  their  advantages  and  disadvantages.) 

2.  Articles  by  WILLIAM   DENMAN,   K.   P.   RADOVANOVITCH,   L.   K. 

SIVERSEN,  G.  A.  Dow,  J.  H.  HANSEN,  and  B.  LLOYD.  Pacific 
Marine  Review,  Feb.,  1919.  (Description  of  the  efficiency  of 
the  Diesel  engine  and  some  illustrations  of  its  application.) 

3.  "  Bolinder  Bulletin."     H.  Lund  &  Co.     (Description  of  the  semi- 

Diesel  type  of  engine  and  its  advantages.) 

4.  JOHNSON,    E.    R.,   and   HUEBNER,    G.    G. :    Principles  of   Ocean 

Transportation.  D.  Appleton  &  Co.,  New  York,  1918.  Chap. 
IV.  (Brief  description  of  internal-combustion  engines  and 
their  advantages.) 

5.  ALLEN,  P.  R. :     "  Possibilities  of  the  Internal-Combustion  Engine 

Applied  to  Marine  Propulsion."  Cassier's  Magazine,  1911,  Vol. 
40,  pp.  705-736.  (Description  of  internal-combustion  engines 
in  some  detail,  nontechnical,  many  illustrations  and  diagrams.) 

6.  CHALKLEY,  A.  P. :    Diesel  Engines.    Van  Nostrand,  New  York, 

IQI2.     Introduction,  Chaps.  II,  VI,  and  VII.     (Operation  and 
efficiency  of  the  Diesel  engine.    Technical  in  character.) 
7.  MORRISON,  L.  H. :     Oil  Engines.    Ms-Graw-Hill  Co.,  New  York, 
1919.     (One  of  the  later  volumes  on  the  subject,  technical  in 
character.) 

8.  MATHOT,  R.  E. :    Internal  Combustion  Engines.    Van  Nostrand, 
New  York,  1910. 

9.  Encyclopedia   Americana,   Article   on   "  Internal-Combustion    En- 

gines." 

10.  O'DONNELL,    E.    E. :     The   Merchant   Marine   Manual.     Boston, 

1918.  Pp.  124-132;  163-167.  (Description  of  the  operation 
of  the  oil-burning  engine,  diagram  of  the  Diesel  engine  and 
description  of  its  care  and  supervision.) 

11.  See  also  the  bibliography  published  in  Reference  i,  page  220,  and 

the  current  files  of  Pacific  Marine  Review,  The  Marine  Review, 
International  Marine  Engineering,  Transactions  of  the  Institu- 
tion of  Naval  Architects,  The  Engineer,  Proceedings  of  Insti- 
tute of  Marine  Engineers,  Journal  of  American  Society  of 
Naval  Engineers,  and  Cassier's  Magazine. 


PART  II 

THE  MEASUREMENT  OF  MERCHANT 
VESSELS 


CHAPTER  VIII 

KINDS  OF  TONNAGE  AND  THEIR  USES 
VARIOUS  MEANINGS^OF  TONNAGE 

There  seems  to  be  in  maritime  matters  a  greater  tendency  than 
elsewhere  to  use  the  same  word  in  different  senses,  a  tendency 
which  necessarily  promotes  confusion  and  mistakes.  Nowhere  is 
this  more  evident  than  in  the  expression  "  tonnage,"  a  term  sus- 
ceptible of  at  least  five  meanings  in  connection  with  the  merchant 
marine,  not  to  mention  additional  significance  in  the  navy.  The 
various  kinds  of  tonnage  may  be  classified  as  follows : 

i.  With  Reference  to  the  Object  to  Be  Measured.—  The  ton 
as  a  unit  of  measurement  is  applied  to : 

A.  The  Cargo  Carried,  as  a  unit  of  weight  ("  weight  ton  ")  or 
of  volume  ("space  ton"). 

B.  The  Vessel,  also  as  a  unit  of  either  weight  or  volume,  ex- 
pressed as  displacement,  dead-weight  or  register  tonnage.     This 
application  of  the  same  unit  in  the  measurement  of  several  re- 
lated objects  itself  causes  confusion.     For  example,  the  expres- 
sion "  dead-Aveight  tonnage  "  without  qualification  might  be  used 
to  describe  either  the  cargo  or  vessel,  although  the  context  usually 
makes  the  meaning  in  such  cases  clear. 

II.  With  Reference  to  the  Method  of  Measurement. —  The 
"  ton  "  as  a  unit  of  measurement  may  be  employed  to  represent 
either  weight  or  volume. 

A.  Weight  Tonnage,  in  two  forms : 

i.  Displacement  Tonnage,  or  the  Weight  of  a  Vessel  as  Meas- 
ured by  the  Weight  of  the  Water  Displaced.  The  ton,  in  this  con- 
nection, is  usually  of  2240  pounds  avoirdupois  but  may  also  signify 
a  metric  ton  of  2204.62  pounds  avoirdupois,  a  possibility  which 
augments  the  confusion.  Furthermore,  displacement  is  used  in 
more  than  one  qualified  sense  as  expressing  (a)  the  weight  of  the 
vessel  fully  loaded,  termed  "  displacement  loaded  "  or  "  maximum 
displacement " ;  (b)  the  weight  of  the  vessel  without  cargo  or  fuel, 
termed  "light  displacement";  and  (c)  the  weight  of  the  vessel 
'  137 


i38  MERCHANT  VESSELS 

partly  loaded  at  a  given  moment,  intermediate  between  the  two 
preceding  weights,  termed  "  actual  displacement." 

2.  Dead-weight  Tonnage. —  This  is  a  measure^ oljhe  capacity 
of  a  vessel  expressed  inj:erms  of^jthe  weight  of  the  carj^ujQind 
the"7'  ton  "  may  again  mean  2240  or  2204.62^  pounds  avoir3upois ; 
usually  the  forme^  The  "  maximum  dead  weight  "  is  the  greatest 
weight  of  cargo  the  vessel  can  safely  carry,  while  the  "  actual 
dead  weight "  is  the  weight  on  board  at  a  given  moment. 

B.  Volume  Tonnage,  in  three  formss 

1.  Gross  Tonnage.-f  Every  vessel  is  measured  as  a  prerequisite 
to  registration  and  gross  tonnage  is  one  form  of  register  ton- 
nage, ylt  is  a  measure  of  the  total  "  closed-in  "  space  of  the  vessel, 
after  certain  exemptions  from  measurement  have  been  allowed. 
The  ton  in  this  case  represents  100  cubic  feet  of  space,  a  figure 
which  was  taken  as  a  measure  of  convenience  and  policy>    When 
the  present  system  of  measuring  was  devised  in  England  it  was  de- 
sirable that  the  results  attained  should  not  be  radically  different, 
for   vessels    in   general,    from    those   attained    under    the    older 
measurement  system.     It  was  found  that  the  tonnage  under  the 
old  system  aggregated  3,700,000  tons.     By  the  new  system  of 
measurement  the  aggregate  capacity  of  the  British  merchant  fleet 
was  found  to  be  363,412,456  cubic  feet.     The  ratio  of  existing 
tonnage  to  new  capacity  was  therefore  I  to  98.22,  but  for  con- 
venience this  was  taken  as  i  to  100. 

2.  Net  Tonnage. —  Another  form  of  register  tonnage  is  the  "  net 
ton,"  also  representing  TOO  cubic  feet  and  obtained  by  a  measure- 
ment similar  to  that  employed  for  gross  tonnage.     The  net  ton- 
nage of  a  vessel  is  the  gross  tonnage  less  deductions  for  space 
not  utilized  in  earning  freight  and  therefore  is  supposed  to  rep- 
resent approximately  the  earning-power  space  of  a  vessel.     Both 
gross  and  net  tonnage  depend  upon  the  rules  under  which  they 
are  measured,  rules   which   are   far   from  uniform.     The  gross 
and  net  tonnages  under  different  rules  are  therefore  not  exactly 
comparable. 

3.  Freight  Tonnage. —  Cargo  is  often  measured  on  the  basis  of 
its  volume  instead  of  its  weight.     The  freight  "  ton  "  in  this  case 
represents  40  cubic  feet  of  space. 

It  is  evident  that  with  so  many  meanings  attaching  to  the  word 
"  ton  "  its  use  necessitates  considerable  care  to  avoid  misunder- 
standing. It  is  a  convenient  unit  for  a  great  many  purposes. 


KINDS  OF  TONNAGE  AND  THEIR  USES 


139 


RELATIONS  BETWEEN  VARIOUS  FORMS  OF  TONNAGE 

The  relation  of  net  tonnage  to  gross  tonnage  will  vary  accord- 
ing to  (a)  the  measurement  rules  employed,  and  (b)  the  type 
of  vessel.  The  following  table  shows  thejjifference  between  net 
and  gross  tonnage  under  the  various  nations'  measurement  rules.1 


Flag 


Gross 


Net 


Per  cent  of 
net  to  gross 


United  States   

1,430,011 

qiq.cjot; 

66 

17,040,862 

10,893,898 

61 

Denmark  

668,836 

391,788 

5Q 

Netherlands  

982,104 

607,286 

68 

France  

1,  441;,  422 

83^,016 

58 

Germany    

3,0^0,147 

2,416,370 

61 

Italy  

08^,716 

^07,640 

61 

Taoan 

I  064  1  60 

67  q  083 

64 

Norway 

i  ^8^  6^1 

838  320 

63 

Russia  

687,231 

400,761 

59 

Spain       .  . 

746  O4  7 

4^0  108 

62 

Sweden  . 

7^6.000 

44Q.872 

60 

This  merely  illustrates  the  fact  that  net  tonnage  is  naturally 
a  variable  quantity  under  divergent  measurement  rules.  While 
the  ratio  of  net  to  gross  tonnage  of  steamers  ranges  from  55  to 
65  per  cent  of  gross,  the  ratio  for  sailing  vessels  is  about  87 
per  cent  because  of  the  absence  of  propelling  engines  and  coal 
bunkers. 

Naturally  there  is  little  relation  between  register  tonnage  and 
displacement.  It  is  true,  of  course,  that  beyond  a  certain  point 
additional  strength  and  weight  is  necessary  in  order  to  attain 
a  large  gross  or  net  tonnage  but  two  vessels  of  similar  displace- 
ments may  vary  widely  as  regards  gross  and  especially  net  ton- 
nage. Nor  would  the  relation  be  of  any  particular  commercial 
value  if  ascertained.  A  relation  does  exist  between  displacement 
and  dead  weight ;  since  the  displacement,  loaded  or  actual,  measures 
the  weight  of  the  vessel  and  cargo  on  board  .while  light  displace- 
ment measures  the  weight  of  the  vessel,  the  difference  gives  the 
dead-weight  tonnage.  This  shows  the  capacity  of  the  vessel  if 
loaded  entirely  with  heavy  commodities. 

1  Adapted  from  "  Report  on  Panama  Canal  Traffic  and  Tolls,"  Washing- 
ton, 1913.  8s.  Figures  are  for  IQIO. 


140  MERCHANT  VESSELS 

The  only  remaining  relation  to  be  considered  is  that  between 
registered  tonnage  and  cargo-carrying  ability,  and  this  involves 
the  whole  question  of  how  accurately  vessel  measurement  ap- 
praises the  potential  earning  power  of  the  vessel.  Cargo  may, 
in  general,  be  divided  into  two  classes,  (i)  that  of  great  density 
and  comparatively  small  volume,  such  as  cement,  pig  iron,  iron 
and  steel  manufactures,  grain,  coal,  etc.;  (2)  that  of  relatively 
light  weight  and  considerable  bulk,  such  as  package  freight  and 
general  merchandise.  Since,  in  general,  the  first  type  is  charged 
for  on  the  basis  of  weight  and  the  second  on  the  basis  of  space, 
a  combination  of  both  furnishes  the  greatest  number  of  tons  of 
paying  freight.  Heavy  cargo  would  load  the  vessel  down  to  the 
load  line  without  fully  utilizing  the  capacity,  and  light  freight 
would  entirely  fill  the  vessel  without  bringing.it  to  sufficient  draft. 
A  modern  shelter-deck  steamer  can  be  loaded  with  measurement 
cargo  exceeding  in  measurement  tons  its  dead-weight  capacity  in 
weight  tons.  For  example,  a  vessel  of  4640  tons  gross  register 
tonnage  has  a  dead-weight  capacity  of  8500  tons  and  can  be 
loaded  with  9500  tons  of  measurement  cargo.  Another  vessel  of 
the  well-deck  type  has  a  gross  tonnage  of  5400,  a  dead-weight 
capacity  of  8515  tons,  and  space  for  8500  tons  of  measurement 
cargo.  Loaded  cargo  steamers  carry  on  the  average  about  2^4 
tons  of  dead-weight  freight  for  each  net  ton.  The  ratio  of  net 
tonnage,  gross  tonnage,  and  dead  weight  is  as  I  to  il/2  to  2%. 
By  combining  weight  and  measurement  cargo  the  ratio  may  be 
made  I  to  il/2  to  2^4.  An  investigation  in  1899  showed  that  the 
ratio  of  cargo  tonnage  to  net  tonnage  of  vessels,  steam  and  sail, 
in  the  world's  commerce  was  about  \^/\  to  i.  This  smaller  figure 
results  from  the  many  different  trades  included  and  the  opera- 
tion of  vessels  only  partly  loaded  or  sailing  in  ballast.  TJie  ex- 
tent to  which  vessel  measurement  gauges  the  potential  earning 
power  is  discussed  more  fully  later. 

USES  FOR  VESSEL  TONNAGE 

This  discussion  will  be  divided  into  two  parts ;  the  first  dealing 
with  weight  tonnage,  in  the  form  of  displacement  and  dead-weight, 
and  the  second  with  measurement  tonnage,  in  the  form  of  gross 
and  net  register  tonnage.  Their  uses  are  given  here ;  their 
calculation  in  chapters  IX,  X,  XI  and  XII. 


KINDS  OF  TONNAGE  AND  THEIR  USES  141 

I.  Displacement  and  Dead-Weight  Tonnage. — 

A.  Statistical  Purpose^. —  The  dead-weight  ton  is  often  used  as 
a  unit  for  the  measurement  of  shipping  and  commerce,  as  illus- 
trated by  the  following  cases : 

1.  Comparison  of  the^  Merchant  Marine. —  While  registeMfon- 
nage  is  more  frequently  used  for  this  purpose  the"  deadweight 
ton  has  recently  achieved  prominence  by  reason  of  its  use  by  the 
Shipping  Board  during  the  World  War.     Thus,  this  was  a  common 
basis  for  describing  the  size  of  the  fleet  in  operation,  and  the 
figures  of  overseas  army  transportation  were  kept  by  the  War 
Department  in  a  similar  manner.     The  displacement  ton,  how- 
ever, is  the  common  unit  of  measurement  for  war  vessels,  and 
furnishes  the  legal  measurement  in  Great  Britain  for  this  pur- 
pose.    Thus    when    we    say    that    Great    Britain    possesses    the 
largest    navy    in    the    world    we    are    referring    to    displace- 
ment tonnage. 

2.  Shipbuilding  Comparisons. —  The  dead-weight  tonnage  is  a 
common  figure  for  the  measurement  of  the  extent  and  progress  of 
shipbuilding.     Its  annual  reports  show  that  the  maximum  program 
of  the  Shipping  Board  up  to  June  30,  1919,  was  17,399,961  dead- 
weight tons,  of  which  3,783,125  tons  had  been  canceled  or  sus- 
pended, leaving  a  net  program  of  13,616,836  dead-weight  tons. 
Of  this  301,809  dead-weight  tons  were  delivered  in  1917,  2,987,- 
377  in  1918  and  2,568,978  in  1919  or  a  total  of  5,858,164,  leaving 
7,758,672  tons  to  be  delivered. 

3.  Cost  Comparisons. —  The  dead-weight  ton  is  frequently  used 
as  a  basis  for  comparing  shipbuilding  costs.     We  find  cited  in 
texts,  for  example,  that  "  English  yards  would  bid  $37.50  per 
dead-weight  ton  against  the  lowest  American  bid  of  $55  " ;  that 
"  the  bid  in  England  would  be  $32  as  against  $50  in  the  United 
States."     Labor    costs    and    costs    of    operation    are    sometimes 
similarly  compared.     Thus,  during  the  World  War  it  was  esti- 
mated that  on  vessels  costing  $215  per  dead-weight  ton  the  return 
on  investment  ought  to  be  $5.10  per  dead- weight  ton  per  month, 
estimating  depreciation  at  the   rate  of   10  per  cent  per  annum 
for  the  first  three  years  and  5  per  cent  thereafter  on  the  estimated 
normal  cost  of  $100  per  dead-weight  ton,  amortization  of  33% 
per  cent  per  annum  for  three  years  of  the  difference  between  war- 
time and  normal  costs,  and  interest  at  5  per  cent  per  annum. 


142  MERCHANT  VESSELS 

This  is  merely  cited  as  an  illustration  of  the  dead-weight  ton  used 
as  a  unit  of  calculation  for  statistical  purposes. 

4.  Dead-weight  Tonnage  as  a  Basis  for  Conference  Agree- 
ments.—  Agreements  respecting  freight  traffic  for  the  purpose  of 
regulating  competition  are  common  in  the  line  traffic.  These 
agreements  sometimes  provide  for  a  division  of  the  service  and 
the  profit  between  various  lines,  often  on  a  tonnage  basis.  Thus 
it  was  shown  by  a  Congressional  investigation  that  the  lines  be- 
tween New  York  and  Australia  had  agreed  to  divide  the  trade 
between  three  lines,  one  furnishing  42^.  per  cent  of  the  tonnage 
(presumably  dead-weight),  one  furnishing  35  per  cent  of  the  ton- 
nage, and  one  22^2  per  cent.  The  profits  were  to  be  divided  in 
similar  proportions.  Similar  agreements  have  been  found  in  other 
trades. 

B.  Legal  Purposes. —  The  dead-weight  and  displacement  ton 
is  uncommon  as  a  legal  unit,  but  indirectly  it  figures  as  a  basis  for 
the  proposed  English  freeboard  rules  in  the  calculation  of  the 
coefficient  of   fineness,  the  formula  being  35  times  the  molded 
displacement  in  tons  at  a  molded  draft  which  is  85  per  cent  of 
the  molded  depth  of  the  freeboard  deck  divided  by  length  times 
breadth  times  the  above  draft.     The  use  made  of  this  formula  is 
described  in  the  next  chapter. 

C.  Taxation  Purposes. — 

1.  Tonnage  Taxes. —  Dead  weight  has  served  in  the  past  as  a 
basis   for  the   assessment  of  tonnage  taxes   levied   for  the   use 
of  navigable  waters  and  port  facilities  but  has  largely  been  re- 
placed by  net  registered  tonnage.     An  Admiralty  committee  in 
England  in  1821  held  that  dead-weight  capacity  was  the  fairest 
basis  for  tonnage,  and  early  English  rules  measured  dead-weight 
tonnage,   rather   than  internal  volume.     Displacement   has   been 
urged  also  as  a  measure  of  a  vessel's  capacity  and  was  discussed 
in  the  Report  of  the  Tonnage  Commission  of  1881. 

2.  Tolls. —  Both  dead-weight  and   displacement  tonnage  have 
been  suggested  as  a  basis  for  the  assessment  of  tolls  levied  on  mer- 
chant vessels  for  the  use  of  canals  and  river  improvements  but 
have  never  been  favorably  considered  for  this  purpose,  all  the 
prominent  canals  having  adopted  register  tonnage  for  this  pur- 
pose.    On  the  other  hand,  the  Panama  Canal  rules  have  adopted 
displacement  tonnage  as  the  fairest  basis  for  the  levy  of  tolls  on 
warships.     Net  registered  tonnage  is  a  misused  term  in  connec- 


KINDS  OF  TONNAGE  AND  THEIR  USES  143 

tion  with  these  vessels  because  it  indicates  the  earning  capacity 
of  a  vessel  and  the  warship  is  designed  as  a  whole  for  a'  par- 
ticular purpose.  Furthermore,  the  system  of  measurement  in  use 
is  designed  for  merchant  vessels  and  to  apply  it  to  war  vessels 
is  a  cumbersome  process.  The  Suez  Canal  uses  it  for  this  pur- 
pose, but  the  actual  measuring  is  done  by  the  respective  nations 
owning  the  vessels.  The  rules  give  a  widely  fluctuating  ratio 
of  net  tonnage  to  normal  displacement,  showing  their  highly  ac- 
cidental results.  Displacement  tonnage  has  the  advantage  of 
being  easily  determined  by  a  comparison  of  the  draft  of  the 
vessel  and  its  "  displacement  curve,"  described  in  the  next  chapter. 
Mr.  R.  H.  M.  Robinson,  a  naval  expert,  testified  that : 

The  displacement  of  a  warship  is  the  most  accurate  means  of 
estimating  the  value  of  that  warship  or  the  power  of  that  warship. 
It  is  not  an  absolutely  accurate  measurement,  but  it  is  the  most 
accurate  measure  you~couicT  name.  If  a  ship  has  20,000  tons  displace- 
ment it  is  reasonable  to  presume  that  it  is  twice  as  valuable  from 
the  military  standpoint  as  a  io,ooo-ton  ship. 

It  is  also  considered  a  standard  which  is  reasonably  fair  as  be- 
tween different  classes  of  warships.  The  Panama  Canal  tolls 
have  been  fixed  for  such  vessels  at  50  cents  per  displacement  ton. 

D.  Charges  for  Services  Rendered. —  Dead-weight  tonnage  oc- 
casionally may  serve  as  a  basis  for  charges  for  services  rendered 
to  a  vessel  entering,  leaving,  or  lying  at  a  port;  displacement  is 
never  used  for  this  purpose  though  it  has  been  proposed  as  a  basis 
for  the  levy  of  dock  charges. 

i.  Pilotage  Fees. —  Dead  weight  or  displacement  seldom  serves 
as  a  basis  for  pilotage  fees  except  indirectly  as  a  factor  in  the 
draft  of  the  vessel.  It  is  mentioned  in  this  connection,  however, 
by  foreign  writers.  The  same  is  true  of  services  rendered. 

E.  Description  of  Vessels. —  Displacement  is  frequently  used  in 
this  connection  for  war  vessels,  as  previously  indicated,  though 
it  has  many  limitations.     Dead  weight  is  important   for  cargo 
vessels. 

i.  In  Shipbuilding. —  One  of  the  most  important  factors  in 
the  building  of  a  vessel  is  the  dead-weight  tonnage.  With  this 
given  to  the  designer  as  a  basis,  he  proceeds  to  figure  the  type 
of  vessel  which  will  be  the  most  economical  for  the  trade  and 
which  will  have  the  lowest  possible  legal  tonnage. 


i44  MERCHANT  VESSELS 

2.  Carrying  Capacity. —  For  vessels  engaged  in  the  carriage  of 
heavy  commodities  dead-weight  tonnage  serves  as  an  approximate 
measure  of  size  and  capacity. 

3.  For  Chartering. —  In  ocean  charters  it  is  common  to  base 
the   remuneration   for   the  hire   of   the '  vessel   upon   the   dead- 
weight tonnage  of  the  vessel.     Thus  the  United  States  Shipping 
Board  paid  from  $5.75  to  $7  per  dead-weight  ton  per  month  for 
vessels  requisitioned  for  government  purposes.     The  shipbroker 
may  also  estimate  the  availability  of  vessels  for  definite  purposes 
on  the  basis  of  their  dead-weight  capacity. 

4.  As  a  Basis  for  Calculations. —  It  is  shown  later  that  displace- 
ment tonnage  may  be  used  as  a  means  of  calculating  cargo  on 
board  and  cargo  discharged,  and  we  have  seen  that   from  the 
loaded  displacement  and  light  displacement  dead-weight  tonnage 
is  found. 

II.  Gross  and  Net  Tonnage. — 

A.  Statistical  Purposes. —  The  most  widespread  use  of  register 
tonnage  is  as  a  unit  for  statistical  purposes.  The  primary  object 
here  involved  is  to  have  some  common  denominator  to  which  the 
volume  of  commerce  and  shipping  of  different  years  and  different 
countries  may  be  reduced  for  purposes  of  computation  and  com- 
parison. This  object  is  very  imperfectly  fulfilled  by  the  register 
ton  as  at  present  constituted.  The  word  "  ton  "  is  susceptible  of 
different  meanings  and  confusion,  the  system  of  measuring  is  not 
uniform  throughout  the  world  and  the  spaces  measured  are  not 
the  same  in  different  countries  and  under  different  rules.  Never- 
theless, this  is  the  only  statistical  unit  at  present  available. 

i.  Register  Tonnage  and  Comparison  of  the  Merchant  Marine. 
-  Thus,  on  June  30,  1919,  the  Commissioner  of  Navigation  re- 
ports that  American  shipping  had  grown  from  a  gross  tonnage 
of  7,928,688  in  1914  to  12,907,300  in  1919.  Even  in  this  com- 
parison of  different  years  in  the  same  country  defects  iti  the 
unit  of  measurement  are  apparent!  Subsequent  to  1915  shelter- 
deck  spaces  and  closed-in  spaces  were  mdre^irbefalry  Treated  than 
previously,  and  while  the  difference  between  1914  and  1916,  for 
example,  is  probably  not  great  the  "Hgures  are  not  theoretically 
comparable.  How  much  greater  is  the^lfiigcTepancy  when  we  at- 
tempt to  make  a  comparison  between  the  "net  tonnage  of  1919 
and  1890  at  which  earlier  date  a  differenfTtilmg  Tor  propelling- 


KINDS  OF  TONNAGE  AND  THEIR  USES  145 

space  deductions  was  in  force;  or  between  the  gross  tonnage  of 
1919  and  1860,  at  which  earlier  date  the  Moorsom  system  of 
measurement  had  not  yet  been  adopted.  In  his  report  for  1919 
we  find  also  a  comparative  table  of  steam  and  sail  tonnage  on  the 
basis  of  gross  tonnage.  A  comparison  of  net  tonnage  for  the 
two  classes  is  not  satisfactory  because  of  the  deductions  made  in 
steam  vessels  for  space  occupied  by  engines.  Strictly  speaking, 
the  proportion  of  steam  gross  tonnage  to  total  gross  tonnage  in 
1910  and  1919,  for  example,  would  not  be  comparable  because 
of  slight  changes  in  the  rules.  These  comparisons  become  much 
less  exact  when  made  between  the  merchant  fleets  of  different 
countries,  a  purpose  for  which  tonnage  is  also  used.  Thus  we 
find  that  Lloyd's  Register  reports  the  gross  and  net  tonnages 
for  various  countries  and  for  a  series  of  years,  but  comparisons 
between  countries  are  evidently  inexact,  since  the  national  rules 
all  differ.  Time  comparisons  are  likewise  inaccurate  because 
modifications  in  rules  have  been  constantly  occurring.  For  ex- 
ample, the  rules  affecting  net  tonnage  in  the  United  States,  Ger- 
many, Russia,  Holland,  France,  and  Spain  were  all  changed  be- 
tween 1895  and  1904.  In  spite  of  these  limitations  the  indefinite 
register  ton  remains  theTonly  available  unit  and  therefore  must 
be  employed  for  these  purposes. 

2.  Register  Tonnage  Employed  as  a  Measure  of  the  Extent 
and  Progress  of  Shipbuilding. —  Thus,  to  give  an  idea  of  ship- 
building progress  in  the  United  States  we  say  that  the  average 
monthly  gross  tonnage  built  was  27,000  in  1916,  86,000  in  1917, 
227,000  in  1918,  311,000  in  1919,  and  308,000  in  1920.     Com- 
parisons are  similarly  made  between  the  various  countries  of  the 
world. 

3.  Register  Tonnage  Used  for  Comparisons  of  Trade  and  Ship- 
ping,—  For  example,  while  figures  for  the  imports  and  exports 
of  commodities  are  given  in  terms  of  dollars  no  complete  tabula- 
tion is  made  of  their  amount.     Statistics  are  kept,  however,  of 
vessel  entrances  and  clearances  in  terms  of  net  tonnage,  and  we 
can  ascertain  that  nearly  48,000,000  tons  cleared  from  American 
ports  in  1919  and  nearly  45,000,000  tons  entered.     It  is  also  pos- 
sible to  ascertain  from  the  figures  that  of  the  tonnage  entered 
and  cleared  44  per  cent  was  American  and  56  per  cent  foreign. 
An  interesting  application  of  this  type  of  statistics  is  shown  in  the 
estimate  of  the  probable  increase  in  traffic  through  the  Panama 


146  MERCHANT  VESSELS 

Canal,  as  an  important  factor  in  fixing  the  rate  of  toll.  The  ton- 
nage which  could  have  used  the  canal  to  advantage  in  1899  and 
1910  was  ascertained  from  vessel  entrance  and  clearance  figures 
and  from  the  increase  so  divulged  the  probajBpincrease  from 
1910  to  1915  was  estimated.  The  actual  tonriaflB  fell  consider- 
ably short  of  the  estimate.  In  figures  of  vessel*  entrances  and 
clearances  not  only  is  the  divergence  in  net  tonnage  a  disturbing 
factor  but  in  addition  it  must  be  recognized  that  the  methods  of 
recording  such  statistics  are  far  from  uniform.  In  the  United 
States  and  Great  Britain  entrances  are  credited  to  the  first  foreign 
port  from  which  the  vessel  sailed.  In  Italy  when  a  vessel  comes 
from  more  than  one  foreign  country  it  is  credited  to  each  country. 
The  entrance  methods  of  the  United  States  and  Great  Britain 
are  similar;  the  rules  for  crediting  clearances  are  different.  We 
credit  the  clearance  to  the  first  foreign  port  of  discharge  unless 
the'bulk  of  the  cargo  is  destined  elsewhere,  while  vessels  leaving 
Great  Britain  are  credited  to  the  last  port  to  which  cargo  is  con- 
signed. In  1910  in  the  United  States  itself  four  variations  in  the 
methods  of  compiling  these  figures  existed.  It  may  be  said  that 
there  are  unavoidable  duplications  and  omissions  when  consider- 
ing movements  to  and  from  particular  countries  and  over  par- 
ticular trade  routes. 

4.  Comparisons  of  Financial  Results. —  It  is  sometimes  con- 
venient, for  purposes  of  comparison,  to  reduce  financial  results 
to  a  vessel  ton  basis,  or  to  make  comparisons  between  financial 
results  and  vessel  tonnage.     Thus,  since  ocean  freight  rates  and 
charter  rates  depend  upon  supply  and  demand  of  transportation, 
an  explanation  of  existing  rates  and  judgment  of  future  rates 
inevitably  include   a  consideration   of   available   vessel  tonnage. 
Profits  of  shipping  companies  may  be  compared  on  a  tonnage 
basis  and  costs  are  sometimes  also  figured  in  this  manner,  though 
more  frequently  the  dead-weight  ton  is  used. 

5.  Conference    Agreements. —  Agreements    and    combinations 
among  otherwise  competing  steamship  lines  are  common,  the  old 
fallacy  of  absolutely  unrestrained  competition  on  the  ocean  having 
been  thoroughly  disproved.     We  have  previously  shown  the  ap- 
plication of  tonnage  statistics  to  freight  agreements  between  the 
lines.     Before  the  World  War  a  passenger,  agreement  existed 
governing  the  steerage  passenger  traffic  between  the  United  States, 
Great  Britain,  and  a  portion  of  Europe,  the  provision  of  which  was 


KINDS  OF  TONNAGE  AND  THEIR  USES  147 

that  each  line  agreed  to  arrange  its  services  so  that  the  number 
of  steeragers  carried  corresponded  to  the  number  allotted  to  it 
by  the  agreement.  The  lines  furnished  to  the  secretary  a  state- 
ment of  passengers  carried  and  tonnage  used,  from  which  the 
secretary  prepared  monthly  accounts  to  show  how  the  lines  stood 
to  each  other  with  regard  to  tonnage  employed.  For  every  in- 
crease of  1000  tons  (presumably  net  tonnage)  each  line  was  al- 
lowed a  certain  number  of  steeragers,  resulting  from  each  1000 
tons  of  the  total  tonnage  employed  in  the  current  year  by  all  the 
lines.  The  increase  in  tonnage  was  counted  for  70  per  cent  and 
the  decrease  in  tonnage  also  counted  as  70  per  cent  if  the  tonnage 
did  not  decrease  more  than  10  per  cent.  The  agreement  thus 
allowed  the  profitable  lines  to  increase  their  tonnage  in  the  propor- 
tion that  the  trade  showed  justified. 

B.  Legal  Purposes. —  The  ton  unit,  having  been  widely  used 
for  commercial  purposes,  also  became  a  commonly  accepted 
criterion  for  many  legal  purposes. 

1.  Licenses. —  For  example  the  general  navigation  laws  of  the 
United  States  require  that  vessels  in  the  foreign  trade  be  registered, 
a  prerequisite  to  obtaining  a  register  being  the  measurement  of 
gross  and  net  tonnage.     Vessels  of  20  tons  or  upward  engaged 
in  the  coasting  or  fishing  trade  are  officially  enrolled,  while  those 
of  5  tons  but  less  than  20  tons  are  licensed.     Measurement  and 
determination  of  net  tonnage  is  a  universal  requirement  for  the 
official  recognition  of  a  vessel's  status,  and  in  practice  the  ship's 
tonnage  papers  are  essential  documents  for  foreign  trade. 

2.  Subsidies  and  Bounties. —  Tonnage   frequently  serves  as  a 
basis   for  government  aid  to  shipping  and   shipbuilding.     Thus, 
France  pays  $27.99  Per  gross  ton  to  iron  and  steel  vessels  con- 
structed at  home  and  $18.34  to  sailing  vessels  so  constructed. 
Under  the-  law  of  1906  equipment  bounties  are  paid  which  de- 
pend on  the  tonnage  of  the  vessel,  days  in  commission,  character 
of  propelling  power,  speed,  quantity  of  cargo,  and  average  daily 
run.     For  steamers  the  grant  is  4  centimes  per  ton  per  day  for 
the  first  3000  tons,  3  centimes  additional  for  each  ton  between 
3000  and  6000  tons,  and  2  centimes  additional  for  each  ton  be- 
tween 6000  and  7000  tons.     These  are  increased  for  vessels  of 
14  knots  and  over.     In  Japan  construction  bounties  are  granted 
on  large  vessels  on  the  gross  tonnage  basis  and  general  naviga- 
tion bounties  on  the  same  basis.     The  Austrian  law  of  1893  pro- 


148  MERCHANT  VESSELS 

vided  for  subventions  based  on  net  tonnage,  but  most  modern 
laws  are  based  on  gross  tonnage.  If  the  subsidies  based  upon 
gross  tonnage  are  large  enough  the  natural  tendency  is  to  attempt 
to  enlarge  the  gross  tonnage  of  vessels  entitled  to  subsidies  on 
this  basis,  as  the  subsidies  received  more  than  compensate  for  any 
extra  tonnage  taxes  and  port  charges  so  incurred. 

3.  Limitation  of   Damages. —  To   prevent  small  vessels   from 
being  assessed  with  damages  out  of  proportion  to  their  size  in 
cases  of  collision  where  their  responsibility  would  otherwise  so^ 
result,  laws  are  found  which  limit  the  liability.     In  the  United 
States  the  extent  of  this  limitation  is  the  value  of  the  vessel  and 
the  freight  money  earned  on  the  voyage,  but  in  England  the  legal 
limitation  is  fixed  at  8  pounds  sterling  per  gross  ton  in  the  event 
of  property  damage  and  7  pounds  sterling  per  ton  additional  if 
there  be  loss  of  life  or  personal  injury.     The  legal  liability  is 
virtually  fixed,  therefore,  on  the  basis  of  the  tonnage  and  not  the 
value  of  the  vessel. 

4.  Tonnage  as  Evidence. —  Inasmuch  as  custom  has  made  the 
registered  tonnage  a  common  method  of  estimating  the  size  and 
capacity  of  vessels  the  courts  have  been  moved  to  recognize  and 
infer  registered  tonnage  where  the  expression  "  ton  "  has  been 
used  without  qualification.     Thus,  an  ordinance  of  the  city  of 
New  Orleans  required  ocean  steamships  arriving  "  from  sea  "  and 
landing  at  any  city  wharf  to  pay  from  15  to  20  cents  per  ton 
wharf  dues.     The  court  said  in  the  Thomas  Melville,  62  Fed. 
751,  "The  word  'ton/  in  the  ordinance  and  amendments  thereto 
controlling  this  case,  as  applied  to  the  measurement  of  vessels, 
has  a  certain  definite  meaning,  well  settled  by  custom  and  by  the 
navigation  laws  of  the  United  States,  and  it  means  100  cubic  feet 
of  interior  space." 

5.  Classification  for  Legislative  Purposes. —  It  is  common  to  use 
gross  tonnage  as  a  measure  to  distinguish  vessels  of  different  sizes 
in  legislative  acts.     Thus,  for  example,  steamers  of  over  700  gross 
tons  carrying  passengers  for  hire  may  be  required  to  have  hull 
and  boilers  inspected  by  the  government.     In  subsidy  and  subven- 
tion acts  the  grants  to  vessels  are  sometimes  classified  in  accord- 
ance with  the  size  of  the  vessel  on  this  basis. 

C.  Tonnage  as  a  Basis  for  Taxation. —  Tonnage  from  the 
earliest  times  has  served  as  a  basis  for  taxation.  This  was,  in 
fact,  the  origin  of  the  measurement  of  vessels  in  England  and  has 


KINDS  OF  TONNAGE  AND  THEIR  USES  149 

now  become  a  world-wide  factor  in  determining  vessel  construc- 
tion and  net  register  tonnage. 

i.  Tonnage  Taxes. —  These  taxes  are  universally  levied  as  a 
charge  for  the  use  of  the  navigable  waters  under  national  juris- 
diction, though  they  may  to  some  degree  be  regarded  as  a  com- 
pensation for  the  service  of  maintaining  the  safety  and  convenience 
of  a  port.  We  distinguish  such  taxes  from  charges  for  services 
rendered,  which  are  discussed  later.  While  tonnage  taxes  are 
assessed  at  practically  all  ports  of  the.  world  it  is  sufficient  for  the 
purpose  of  illustration  to  confine  attention  to  the  United  States. 
Here  the  power  of  the  federal  government  over  foreign  com- 
merce and  the  specific  prohibition  of  the  Constitution  against 
tonnage  and  customs  duties  without  Congressional  consent  pre- 
cludes the  states  from  exercising  such  tonnage  taxation.  Prior 
to  1882  the  federal  government  levied  a  tax  of  30  cents  per  annum 
per  gross  ton  on  vessels  entering  American  ports  from  abroad. 
In  1882  tonnage  taxes  were  placed  upon  a  net  tonnage  basis,  and 
at  present  a  tax  of  2  cents  per  ton  is  imposed  upon  all  vessels 
entering  from  ports  in  North  America,  Central  America,  West 
Indies,  Bahama  or  Bermuda  Islands,  South  American  Coast 
bordering  on  Caribbean  Sea  or  Newfoundland,  and  a  tax  of  6 
cents  per  ton  on  all  vessels  entering  from  other  foreign  ports, 
irrespective  of  ownership.  It  is  not  levied  on  more  than  five 
entries  during  any  one  year  at  the  same  rate,  and  laws  exist 
which  permit  reciprocal  arrangements  with  foreign  nations  which 
agree  to  exempt  or  partially  exempt  our  vessels  from  similar 
taxation.  The  navigation  laws  provide  for  alien  tonnage  taxes  on 
vessels  of  nations  which  discriminate  against  the  United  States 
ot  trom  30  to  50  cents  per  ton.  A  state  may  levy  a  tax  upon 
the  property  of  its  citizens,  including  vessel  property,  but  not  upon 
registered  tonnage.  Without  taking  space  to  consider  the  various 
court  decisions  respecting  federal  and  state  taxation  powers,  it 
may  therefore  be  rather  crudely  stated  that  "  tonnage  "  has  be- 
come practically  a  term  distinctive  of  federal  taxation  through 
decisions  preventing  states  from  levying  taxes  on  this  basis.  A 
statute  of  Maine  provides  for  the  assessment  of  sailing  vessels 
on  the  basis  of  an  arbitrary  value  per  gross  ton,  decreased  an- 
nually with  the  vessel's  age.  Indiana  requires  owners  of  vessels 
to  pay  an  annual  tax  of  3  cents  per  net  registered  ton  in  lieu  of 
all  other  taxes,  and  Minnesota  has  a  similar  law.  The  states 


150  MERCHANT  VESSELS 

regard  these  laws  as  property  taxes  and  not  tonnage  laws.  As 
previously  stated,  such  tonnage  taxes  are  found  in  other  countries 
also.  For  a  discussion  as  to  whether  register  tonnage  is  an 
equitable  basis  for  taxation  see  the  chapter  on  net  tonnage. 

2.  Tonnage  as  a  Basis  for  Tolls. —  In  addition  to  charges  for 
the  use  of  ports,  vessels  using  canals  are  ordinarily  subjected 
to  the  payment  of  tolls.  Such  tolls  are  in  some  cases  practically 
a  charge  for  services  rendered,  designed  to  make  the  canal  self- 
supporting,  and  in  others  yield  a  profit.  All  merchant  vessels 
using  the  Panama  Canal  are  charged  $1.20  per  net  ton  by  Panama 
rules,  with  a  deduction  of  40  per  cent  for  vessels  in  ballast,  sub- 
ject to  the  limitation  that  the  tolls  shall  not  exceed  $1.25  per  net 
ton  as  calculated  under  United  States  measurement  rules.  For 
the  use  of  the  Suez  Canal  the  toll  on  merchant  vessels  was  $1.21 
per  net  ton,  but  this  figure  was  increased  during  the  World  War 
until  the  rate  reached  $1.64  per  net  ton.  These  tolls  yield  a  hand- 
some profit.  The  Kiel  Canal  connects  the  North  and  Baltic  Seas, 
and  for  its  use  prior  to  the  World  War  tolls  on  net  tonnage 
according  to  the  size  of  the  vessel  were  charged.  These  ranged 
from  .6  mark  per  net  register  ton  for  the  first  400  tons  to  .2 
mark  per  ton  for  each  ton  above  800  net  tons,  with  a  minimum 
of  10  marks  per  vessel.  The  Corinth  Canal  connects  the  Gulf  of 
Corinth  with  the  Gulf  of  Aegina.  The  toll  charges  are  based 
on  net  tonnage  and  vary  with  the  type  of  vessel  and  the  route 
over  which  it  operates.  Tolls  are  also  collected  by  private  com- 
panies and  the  states  for  the  use  of  river  improvements  and 
canals,  usually  on  the  basis  of  tonnage. 

D.  Tonnage  as  a  Measurement  of  Services  Rendered. —  In  ad- 
dition to  taxes  a  vessel  is  put  to  additional  expense  for  various 
services  rendered  at  a  port.  The  value  of  these  services  to  the 
vessel  is  usually  gauged  by  the  size  of  the  vessel  as  determined 
by  its  tonnage. 

1.  Pilotage  Fees. —  This  includes  the  charges  for  bringing  the 
ship  in  or  out  of  a  harbor  or  through  a  channel.     At  the  port  of 
Boston  this  charge  is  based  on  the  draft  of  the  vessel  and  the 
net  tonnage,  being  $5  per  foot  for  vessels  over  2000  net  tonnage. 
Ordinarily,  however,  such  charges  in  the  United  States  are  based 
simply  upon  draft.     In  France,  pilotage  fees  often  depend  solely 
upon  net  register  tonnage. 

2.  Towage  Charges. —  These  are  charges  for  the  employment 


KINDS  OF  TONNAGE  AND  THEIR  USES  151 

of  tugs  or  towboats  required  to  assist  vessels  into  and  out  of  the 
harbor,  for  docking  and  undocking  or  for  moving  the  vessel  from 
pier  to  pier.  At  Philadelphia  this  charge  varies  with  the  gross 
tonnage  of  the  vessel  and  the  service  rendered  and  at  Savannah 
the  charges  range  from  17  to  20  cents  per  gross  ton  for  towage 
to  and  from  sea.  The  towage  charges  at  San  Francisco  are 
regulated  by  the  net  tonnage  of  the  vessel.  Towage  charges  are 
also  assessed  for  passages  through  canals,  but  not  usually  upon 
a  registered  tonnage  basis. 

3.  Dockage  Charges. —  These  include  all  charges  levied  against 
vessels  for  the  use  of  berthing  space,  for  loading,  discharging, 
repairs,  etc.     At  public  piers  in  New  York,   for  example,  the 
charge  is  2  cents  per  net  ton  up  to  200  tons  and  ^2  cent  per  ton 
for  the  excess.     At  Philadelphia  public  piers  the  charge  is  on  a 
similar  basis.     At  New  Orleans  these  charges  are  on  the  basis  of 
gross  tonnage.     As  an  alternative,  at  some  docks  wharfage  is 
charged  —  a  charge  based  upon  the  amount  of  cargo  passing  over 
the  dock  or  wharf. 

4.  Quarantine  Charges. —  The  states  often  impose  quarantine 
charges  to  defray  the  costs  of  protecting  the  health  of  its  citizens, 
and  such  charges  are  sometimes  regulated  by  the  vessel  tonnage. 
Thus,  at  the  port  of  New  York  a  vessel  of  over  500  tons  gross 
from  a  foreign  port  pays  a  fee  of  $10  while  one  of  500  gross 
tons  or  less  pays  a  fee  of  -$5.     Other  vessels  are  charged  fees 
for  fumigating  and  disinfecting  of  $10  for  each  forecastle  and 
2.y2  cents  per  net  ton  for  vessel  holds. 

5.  Insurance  Premiums. — :  In  Great  Britain  and  recently  in  the 
United  States  mutual  protective  associations  have  been  formed  to 
insure  members  against  the  liability  of  a  vessel-owner  for  damage 
to  the  cargo  in  his  possession  due  to  negligence,  for  injuries  to 
persons   through  the  acts  of   the  owner  or  his  agents   and  the 
liability  under  the  bill  of  lading.     Each  owner  enters  his  vessel 
in  the  association  and  pays  a  fixed  rate  per  ton  for  the  protec- 
tion afforded. 

E.  Description  of  Vessels. —  Tonnage  is  frequently  used  as  a 
means  of  describing  and  comparing  individual  vessels  and  their  at- 
tributes. 

i.  Comparison  of  Vessels. —  We  find,  for  example,  that  the 
progress  in  shipbuilding  in  the  North  Atlantic  trade  may  be  ap- 
proximately indicated  by  a  diagram  of  the  gross  tonnage  of  the 


152  MERCHANT  VESSELS 

prominent  vessels  constructed  for  the  route.  Register  tonnage  is 
also  a  convenient  method  of  indicating  the  relative  sizes  of  two 
vessels,  though  we  shall  find  later  that  it  is  not  a  very  definite 
one. 

2.  Tonnage    Comparisons. —  Interesting   comparisons   are   fre- 
quently made  between  register  tonnage  and  displacement,  register 
tonnage  and  dead  weight,  and  register  tonnage  and  cargo  tonnage. 
These  are  usually  of  value  only  when  all  the  details  for  the  com- 
parison are  available,  owing  to  the  many  individual  circumstances 
which  may  affect  the  result.     For  this  reason  such  comparisons 
are  of  little  general  value. 

3.  Register  Tonnage  as  a  Basis  for  the  Building,  Hire,  or  Pur- 
chase of  Vessels. —  Thus  a  price  may  be  agreed  upon  per  net  or 
gross  ton.     For  example,  in  ocean  trade  it  is  common  for  the 
owner  of  a  vessel  to  furnish  the  crew  and  provisions  of  a  vessel 
and  to  hire  it  to  a  charterer,  the  latter  paying  for  the  fuel  and 
port  expenses  and  a  rental  of  so  much  per  net  registered  ton. 
The  gross  tonnage  is  frequently  the  basis  in  time  charters  of  pas- 
senger vessels.     During  the  World  War  the  Shipping  Board  re- 
quisitioned passenger  vessels  and  paid  for  them  from  $9  to  $11.50, 
per  gross  registered  ton  per  month,  depending  upon  their  speed. 
Since  tonnage  taxes  and  port  charges  form  a  considerable  por- 
tion of  a  vessel's  expenses,  it  may  be  imagined  that  every  owner 
is  anxious  to  have  his  builder  reduce  net  tonnage  to  the  lowest 
possible  figure.     This  naturally  has  its  effect  upon  shipbuilding 
design. 

CARGO  TONNAGE 

Cargo  tonnage  may  be  measured  in  terms  of  either  weight  or 
volume.  The  weight  ton  is  a  long  ton  of  2240  pounds  avoirdupois, 
a  short  ton  of  2000  pounds  or  a  metric  ton  of  2204.63  pounds, 
the  first  being  more  important  in  the  ocean  carrying  trade 
of  the  United  States  and  the  short  ton  only  occasionally  used. 
The  measurement  ton  indicates  40  cubic  feet  of  space  and  is  thus 
a  measure  of  volume  and  not  of  weight,  corresponding  in  this 
respect  to  the  vessel  measurement  ton.  The  origin  of  the  measure- 
ment ton  of  freight  has  been  variously  deduced.  One  explana- 
tion is  that  this  is  approximately  the  amount  of  space  occupied 
by  one  of  the  "  tuns  "  of  wine  which  formerly  played  an  im- 


KINDS  OF  TONNAGE  AND  THEIR  USES  153 

portant  part  in  the  English  trade  with  the  Continent.  Another 
is  that  it  originated  in  the  French  "  tonneau  de  mer,"  which  by 
French  measurement  approximated  42  cubic  feet  but  by  English 
measurement  51  cubic  feet.  A  third  explanation  is  that  this  was 
roughly  the  amount  of  space  occupied  by  a  ton  of  grain,  an  article 
intermediate  between  the  heavy  and  light  varieties  of  cargo. 

It  has  been  previously  explained  that  cargo  naturally  divides  it- 
self into  two  classes,  weight  and  measurement.  A  weight  cargo 
is  one  which  occupies  so  little  space"  in  proportion  to  its  weight 
that  the  amount  carried  by  the  vessel  is  only  limited  by  its  dis- 
placement or  deep  load  line.  A  measurement  cargo  is  one  so 
light  and  bulky  that  the  amount  carried  is  limited  by  the  ves- 
sel's internal  volume.  Naturally,  to  carry  measurement  cargo  on 
a  weight  basis  would  be  a  losing  proposition,  as  would  weight 
cargo  on  a  space  basis  and,  therefore,  in  ocean  tariffs  it  is  common 
to  charge  so  much  per  ton,  weight,  or  measurement,  at  the  ship's 
option,  or  to  specify  a  charge  per  measurement  ton  in  some  cases 
and  per  weight  ton  in  others.  Freight  rates  are  often  quoted  on 
other  units  applying  these  principles  of  space  and  weight,  and 
these  same  results  are  incorporated  in  classified  freight  lists.2 

As  a  result  of  the  indiscriminate  use  of  these  two  units,  figures 
of  cargo  tonnage  are  of  little  use  for  statistical  purposes  unless 
analyzed.  Another  result  of  this  same  distinction  in  cargo  is 
that  while  a  simple  relation  exists  between  vessel  displacement 
and  cargo  tonnage  in  weight,  and  to  a  lesser  degree  between 
register  tonnage  and  space  tonnage  of  cargo,  neither  the  space 
nor  displacement  of  a  vessel  alone  can  give  an  accurate  idea 
of  its  cargo  capacity.  The  most  profitable  loading  is  usually  one 
which  combines  weight  and  measurement  cargo  in  ideal  propor- 
tions,  these  proportions  being  determined  by  the  character  of  the 
cargo. 

The  gross  tonnage  of  a  vessel  is  sometimes  compared  with 
the  dead  weight.  Inasmuch  as  the  freeboard  assigned  in 
Great  Britain  is  largely  a  result  of  the  deck  erections,  as 
previously  described,  the  under-deck  tonnage  is  inapplicable.  The 
following  comparison  was  made  some  years  ago  of  (A)  well- 
decked  vessels  with  short  well  and  gross  tonnage  varying  from 
1500  to  2500  tons,  (B)  an  ordinary  well-decker,  with  long  well, 

2  See  G.  G.  Huebner,  Ocean  Steamship  Traffic  Management,  D.  Appleton 
&  Co.,  New  York,  1920,  229-235. 


154 


MERCHANT  VESSELS 


gross  tonnages  from  noo  to  2300,  (C)  well-deckers  with  wells 
filled  in  by  forecastle  and  bridge  being  joined,  gross  tonnages  from 
2100  to  2500  and  very  similar  to  a  spar-decked  vessel,  (D)  spar- 
deckers,  gross  tonnage  from  1500  to  2700  and  (E)  three-deck 
type,  with  two  decks  laid,  gross  tonnages  from  2500  to  3500. 


Type  of  ship 

Dead-weight  capacity  divided  by 

Weight  of  hull,            Gross 
Machinery  and          Register 
Equipment             Tonnage 

A.  (15  examples)..  .. 
B.  (4  examples)  
C.  (5  examples)  
D    (5  examples)  .... 

{max. 
min. 
mean 
r  max. 
•<  min. 
[mean 
{max. 
min. 
mean 
{max. 
min. 
mean 
{max. 
min. 
mean 

2.40 
1.99 

2.21 
2.28 
1.70 
1.97 
2.48 
2.l6 
2.30 

2-59 
1.97 
2.36 
2.32 
2.00 
2.17 
2.  2O 

1-54 

1-37 
1.47 

I-5I 

1.30 

1-39 
1.46 

i.  60 
1.50 
1-55 
1.66 

1-53 
i.  60 
1.50 

E.  (4  examples)  
Mean  of  the  five  types 

Apparently  the  spar-decked  vessels  carry  the  largest  dead-weight 
cargoes  in  proportion  to  the  weight  of  the  vessel,  while  three- 
deckers  carry  the  largest  dead-weight  cargoes  in  relation  to  register 
tonnage.  The  tonnage  as  given  above  is  under  British  rules. 
The  variations  in  the  ratios  of  dead-weight  capacity  to  register 
tonnage  are  surprisingly  small,  the  average  ratio  being  1.5  to  I. 
Various  means  were  at  one  time  employed  to  estimate  cargo 
space  tonnage  from  the  register  tonnage.  One  rule,  for  example, 
was  to  multiply  the  register  tonnage  under  the  tonnage  deck  by 
i%.  It  was  simply  estimated  that  out  of  every  100  cubic  feet  of 
vessel  capacity,  25  cubic  feet  were  rendered  useless  by  breakage 
of  stowage  by  beams,  knees,  sleepers,  and  the  necessary  carriage 
of  provisions,  water,  and  stores,  leaving  75  cubic  feet  available 
for  cargo.  Dividing  this  by  40  cubic  feet,  a  cargo  space  ton, 
gave  i%.  At  present  this  is  considerably  exceeded,  since  with 


KINDS  OF  TONNAGE  AND  THEIR  USES 


155 


the  improvement  in  shipbuilding  methods  the  stowage  space  is 
less  broken  up  and  the  space  for  water,  is  reduced.  But 
the  engine  space  should  be  deducted,  and  this  bears  no  constant 
relation  to  the  size  of  the  vessel,  as  explained  later.  At  present 
the  builder  furnishes  the  owner  tables  indicating  capacities. 
Variations  in  the  methods  of  measurement  employed  by  the 
builder,  some  making  deductions  for  broken  space,  render  these 

HOLD  CAPACITIES 
(including  hatches) 


Location 

Gross  cubic  feet 

Net  cubic  feet 

Hold  No.  i  

CT  -?6o 

,jQ  -300 

Hold  No.  2  

D  x  »o'~"~' 
C7  /i6o 

CA    C  r/-\ 

Hold  No.  3  

O/ft+w 
21  7  2O 

o4oou 

•22  260 

Hold  No.  4  

^O"/  O^ 

<dj8  7QO 

AC  AOO 

Hold  No  5     . 

•5/1    r  rrj 

4j»4U'J 

'Tween-decks  No   i 

o4o5u 

2^  A^f) 

31,700 

2^   >7^A      f 

'Tween-decks  No.  2  

1  T   TO  C 

«3»7°4 

20  8n8 

'Tween-decks  No.  3  

J1>1U5 
T2  n*7& 

72  cSn 

'Tween-decks  No  4 

I3'97° 
•20  *?Ro 

12,509 
26  802 

'Tween-decks  No.  5  

^y,/ou 
28  O2O 

2^  217 

Storage   

t;,ooo 

4,^OO 

Bridge   

27,864 

2^,4^^ 

Poop  . 

0.76=; 

8,^00 

Total    . 

yi/^J 
^87.428 

.^^6,643 

Note. —  Gross  capacity  calculated  to  top  of  beam,  outer  edge  of  frames 
and  top  of  tank  ceiling:  net  capacity  calculated  to  bottom  of  beams,  inner 
edge  of  cargo  battens  and  top  of  tank  ceiling. 


WATER-BALLAST  CAPACITIES 


Tank 
No.  i  tank   

Capacity  in  tons 
IOO 

No.  2  tank  

108 

No.  3  tank   

22  Z 

No.  4  tank   

No.  5  tank  

No.  6  tank   . 

200 

No.  7  tank 


Qi 


Fore  peak  tank  99 

After  peak  tank   65 

Deep  tank  678 


Total    

No.  5  tank  (feed  water) 


i,749 
83 


Total    1,832 


156 


MERCHANT  VESSELS 


results  to  some  extent  uncertain.  The  accompanying  illustration 
for  a  cargo  vessel  of  5125  gross  tons  shows  the  information 
customarily  furnished. 

COAL  BUNKER  CAPACITIES 


Location 

Tons 

Cubic  feet 

No.  3  hold  

^2 

27.77O 

Bridge   

648 

27,864 

Midship  'tvveen-decks      

2=^ 

1  0,96  s 

'Tween-decks  under  bridge   

12  Z 

17,078 

12 

516 

Total    . 

I.7Q2 

77,o$3 

For  purposes  of  stowage,  books  have  been  compiled  giving  the 
results  of  measurement  and  experience,  as,  for  example,  Stevens. 
Here  may  be  found  tables  giving  comparisons  of  space  and 
weight  for  different  commodities  in  various  conditions  and  forms 
of  shipment.  The  following  is  an  illustration  of  such  informa- 
tion for  grain : 


Loosely  filled 


Closely  filled 
and  packed 


Pounds      Cubic 

per  feet 

bushel      per  ton 


Pounds      Cubic 

per  feet 

bushel      per  ton 


Wheat 
Red  Winter   

62.0 

4^.7 

68.0 

42.7 

Bombay    ,  

62.0 

4"v7 

68.0 

42.7 

California    

62  Q 

AZ  7 

680 

42  7 

Walla  Walla  

en  o 

4.8  7 

648 

44  7 

Bessarabia  

62  o 

AS.  7 

680 

42  7 

Peas    American 

f   y 

O4  2 

Ad  8 

60  i 

4T  ^ 

Maize 
White  American   

^5.8 

SI  C, 

vy-j 
60  7 

<T1O 

47  7 

Mixed                  .                   .  . 

c,6  c. 

en  Q 

V**.j 

60  7 

47  7 

Oats   Russian             

j^-j 

-3C  Q 

80  o 

wvr.j 

42  4 

680 

Beans,  Egyptian   

CQ  O 

487 

64  2 

448 

Barley.  Enelish   . 

e.o.1 

c.7.4 

U7'^ 

<;6.c; 

;O.Q 

.*. 

CHAPTER  IX 

DISPLACEMENT  AND  DEAD-WEIGHT  TONNAGE 
DISPLACEMENT 

A  ship  floating  in  still  water  displaces  a  certain  volume  of 
water,  greater  or  less,  depending  upon  its  weight.  For  if  a  bowl 
is  filled  to  the  brim  with  water  and  a  block  of  cork  placed  therein, 
some  water,  but  very  little,  will  overflow.  If  a  block  of  oak  is 
placed  afloat,  however,  considerably  more  of  the  fluid  will 
overflow.  If  the  overflowing  water  is  caught  and  weighed 
it  will  be  found  that  its  weight  is  exactly  equal  to  the  weight 
of  the  floating  body.  This  is  an  elementary  law  of  physics 
and  explains  how  the  term  displacement  comes  to  be  applied  to 
merchant  vessels.  The  quantity  of  water  displaced  is  the  "  volume 
of  displacement "  and  the  weight  of  water  displaced  is  termed  the 
"  weight  of  displacement."  The  former  is  expressed  in  cubic 
feet  or  cubic  meters  and  the  latter  in  tons  of  2240  pounds  or  in 
kilograms.  When  we  speak  of  the  displacement  of  a  vessel  we 
mean  the  weight  of  the  vessel  in  tons  of  2240  pounds  as  ascertained 
by  weighing  the  quantity  of  water  displaced  by  the  vessel  when 
afloat. 

Displacement  is  not  in  any  way  connected  with  form  or  dimen- 
sions. Vessels  of  equal  weight  will  have  equal  displacements, 
though  their  forms  vary  greatly,  and  the  weight  of  displacement 
of  a  vessel  is  as  constant  as  its  own  weight.  When  a  vessel  passes 
from  fresh  to  salt  water  the  volume  of  displacement  must  de- 
crease because  of  the  increasing  density  of  the  water;  but  the 
weight  of  displacement  remains"  the  same,  the  smaller  volume  of 
water  being  compensated  for  by  the  greater  weight  per  unit  of 
volume.  To  put  it  in  another~way,  the  weight  of  displacement 
remains  the  same  but  the  displacement  volume  and  draft  change. 
Therefore,  we  find  both  fresh-water  and  salt-water  load  lines 
marked  on  vessels. 

Displacement  and  Buoyancy. —  Unless  the  weight  of  the  ob- 
ject in  question  is  greater  than  the  weight  of  the  water  dis- 


158  MERCHANT  VESSELS 

placed  it  continues  to  float.  The  weight  of  the  water  displaced 
marks  the  limit  of  floating  power  and  measures  the  "  buoyancy  " 
of  the  object.  The  terms  buoyancy  and  displacement  may  there- 
fore be  used  interchangeably 

Forms  of  DisplacemerB^  Displacement  is  denned  as  the 
weight  of  water  displaced^y  a  floating  vessel.  But  the  term 
"  vessel "  is  an  indefinite  one,  for  it  may  refer  to  the  hull  before 
the  machinery  has  been  introduced ;  the  vessel  complete  but  with- 
out any  fuel  or  cargo  on  board ;  the  vessel  fully  coaled  but  partly 
loaded  with  cargo;  or  the  vessel  fully  loaded  and  ready  for  sea. 
These  various  conditions  give  rise  to  customary  and  well-under- 
stood forms  of  displacement.  "  Light  displacement  "  is  the  weight 
of  the  powered  vessel  with  crew  and  supplies  on  board,  but  with- 
out fuel,  cargo,  or  passengers.  "  Loaded  displacement "  is  the 
weight  of  the  vessel  with  crew,  supplies,  and  fuel  on  board  and 
fully  loaded.  Since  we  are  now  speaking  in  terms  of  weight  we 
mean  by  "  fully  loaded  "  the  maximum  weight  of  cargo  and  not 
necessarily  the  maximum  volume  of  cargo.  Thus  the  vessel  may 
be  weighted  down  to  the  highest  point  consistent  with  safety  and 
yet  if  filled  with  articles  of  great  density  considerable  space  will 
remain  unoccupied.  The  volume  and  density  of  cargo  will  both 
influence  the  displacement  of  the  vessel,  and  since  these  vary  from 
time  to  time  the  term  "  actual  displacement  "  originates,  indicating 
the  weight  of  the  vessel  when  loaded  to  any  given  draft.  Light 
displacement  and  loaded  displacement  are  therefore  constants  for 
a  given  vessel  while  actual  displacement  is  a  variable  quantity 
dependent  upon  cargo  carried.1 

It  is  apparent  that  the  weight  of  cargo  might  also  be  measured 
by  its  displacement  and  this,  in  fact,  is  actually  done  indirectly 

1  Displacement  is  an  important  measure  for  war  vessels.  "  Full  displace- 
ment "  in  this  connection  corresponds  to  loaded  displacement  for  merchant 
vessels.  Light  displacement  means  the  displacement  of  a  war  vessel  with 
complete  battery  and  outfit,  but  without  officers,  crew  and  their  effects, 
ammunition  and  stores,  water  for  drinking  and  machinery,  fuel  and  reserve 
feed  water.  The  definition  differs  in  various  countries.  Normal  displace- 
ment is  the  weight  of  a  warship  completely  equipped  with  a  full  comple- 
ment of  officers  and  crew,  their  effects,  full  equipment,  armament  and 
machinery,  and  two-thirds  of  its  full  allowance  of  stores,  coal,  fuel  oil,  and 
water.  There  is  no  international  uniformity  in  the  definition  of  this  dis- 
placement. Actual  displacement  is  the  weght  of  the  vessel  at  a  given 
time.  The  above  are  American  definitions.  For  a  discussion  of  war  vessel 
displacement  see  E.  R.  Johnson's  "  Report  on  the  Measurement  of  Vessels 
for  the  Panama  Canal,"  Washington,  1913. 


DISPLACEMENT  AND  DEAD-WEIGHT  TONNAGE       159 


through  the  extra  displacement  given  to  the  vessel  by  cargo  on 
board. 

Calculation  of  Displacement. —  The  displacement  of  the  ves- 
sel or  weight  of  water  displaced  may  ^measured  in  various  ways  : 

1.  One  method  would  be  to  coll*  the  water  displaced  and 
weigh  it.     This,  however,  is  tedious?  impractical  and  would  not 
enable  one  to  know  the  displacement  until  the  vessel  was  afloat. 

2.  Since  we  know  that  a  cubic  foot  of  sea  water  weighs  close 
to  64  pounds  or  %5  of  a  ton  avoirdupois,  we  can  ascertain  the 
displacement  weight  from  the  displacement  volume.     The  volume 
of  water  displaced  will  be  equal  to  the  under-water  volume  of  the 
vessel,  or,  in  other  words,  the  portion  of  the  hull  below  the  water 
line.     To  find  the  volume  and  consequently  the  weight  of  water 
displaced  it  is  only  necessary  to  find  the  volume  of  the  vessel 
below  the  water  line.     This  is  the  accurate  method  adopted  by 
the  naval  architect,  the  necessary  dimensions  being  ascertainable 
from  the  drawings.     As  the  Moorsom  method  and  Simpson's  rule 
are  applied  to  find  the  total  volume  of  a  vessel  (see  page  182) 
so  they  can  be  applied  to  find  the  under-water  volume.     Dividing 
the  immersed  portion  of  the  vessel  into  sections  by  transverse 
vertical  planes  erected  at  equal  intervals   (see  illustration,  page 
183),  the  areas  of  these  transverse  vertical  sections  are  measured 
by  Simpson's  rule  as  described  in  a  later  chapter  and  by  applying 
multipliers  to  these  areas  the  under-water  volume  is  accurately 
obtained. 

3.  It  is  convenient,  however,  to  have  some  briefer  method  of  ap- 
proximating the   displacement,   both  to   save  time   and  to   give 
approximate  results  when  the  necessary  measurements  for  the 
accurate  system  are  lacking.     If  the  under-water  portion  of  a 
vessel  were  in  the  form  of  a  block  with  parallel  sides  its  volume 
and  the  volume  of  water  displaced  by  it  could  be  accurately  found 
by  the  product  of  the  length,  breadth,  and  depth.     This  divided 
by  35  (since  35  cubic  feet  of  sea  water  weigh  one  ton)  would 
give  the  displacement  tonnage.     The  formula  would  be 


35 

But  a  vessel  is  rounded  off  or  "  fined  "  off  toward  the  keel  and 
toward  the  ends  so  that  its  volume  is  considerably  less  than  the 


160  MERCHANT  VESSELS 

volume  of  the  corresponding  block.     We  have  therefore  a  ratio 
Volume  of  vessel  under  water 


Volume  of  block  with  similar  dimensions 

which  will  yield  a  result  lower  than  I,  that  is.  in  the  form  of  a 
percentage.  The  greater  the  rounding-off  and  the  "  finer  "  the 
lines  of  the  ship  the  smaller  this  percentage  will  be,  for  it  ex- 
presses the  relation  between  the  volume  of  the  vessel  and  the 
volume  of  the  block,  being  therefore  known  as  the  "  block  co- 
efficient." The  block  coefficient  may  be  selected  by  considering  the 
qualities  of  the  vessel,  particularly  the  speed.  The  following  are 
a  few  examples  given  by  Walton: 

.8  would  be  a  very  full  vessel. 

•7  to  .75,  an  average  cargo  steamer. 

.65,  a  moderately  fine  cargo  steamer. 

.6,  a  fine  steamer,  such  as  used  for  passenger  service. 

.5,  an  exceedingly  fine  steamer,  but  an  average  for  steam  yachts. 

.5  to  .4,  in  fine  yachts. 

Thus  for  a  vessel  410  feet  long,  56  feet  broad,  and  with  30 
feet  draft,  assuming  a  coefficient  of  .81  the  displacement  would 
be 

4ioX56X3oX.8i 

,  or  15,930  tons 

35 

Or,  given  the  length,  breadth,  mean  draft,  and  displacement  at 
that  draft,  it  is  possible  to  estimate  the  block  coefficient.  The 
formula  becomes 

35  X  15-930 
,  or  .81 

410  X  56  X  30 

The  volume  of  the  under-water  portion  of  the  hypothetical 
block  above  referred  to  will  be  recognized  as  the  "  block  displace- 
ment "  referred  to  in  Chapter  VIII  as  a  possible  basis  for  assess- 
ing tolls  and  charges. 

4.  Since  the  length,  breadth,  and  coefficient  of  fineness  are  con- 
stants for  a  given  vessel  and  the  displacement  varies  with  the 
depth  it  is  convenient  to  figure  at  once  the  displacements  at  various 
depths  and  make  a  record  of  the  same,  so  that  an  officer  of  the 


DISPLACEMENT  AND  DEAD-WEIGHT  TONNAGE      161 

vessel  knowing  the  draft  can  ascertain  from  the  record  the  dis- 
placement, without  calculation.  The  displacements  at  various 
drafts  may  be  ascertained  by  calculations  based  on  the  coefficient 
of  fineness  or  preferably  by  the  Moorsom  system,  and  the  results 
presented  in  graphic  form  (see  Figure  55). 

On  this  diagram  a  vertical   scale  of   displacement  is  plotted 
across  the  top.     The  curve  is  composed  of  the  points  of  inter- 


FlG.   55- — DISPLACEMENT  SCALE 

section  of  various  drafts  and  displacements,  as  figured  by  the 
marine  architect.  At  a  draft  of  9  feet  if  we  draw  a  line  parallel 
to  the  base  of  the  diagram  we  find  that  it  intersects  the  curve 
at  approximately  the  point  4000  on  the  displacement  scale  above. 
Similarly,  a  horizontal  line  drawn  through  the  3<D-foot  draft 
intersects  the  curve  at  a  displacement  of  15,930.  It  is  possible 
by  inspection  of  this  diagram  to  obtain  fairly  accurately  the  dis- 
placement at  any  given  draft  or  the  draft  at  any  given  displace- 
ment. At  the  right  of  the  diagram,  however,  is  a  so-called  verti- 
cal displacement  scale,  combined  with  a  dead  weight  and  free- 
board table.  Column  2  indicates  various  drafts  and  column  I 
indicates  the  displacements  at  these  drafts.  It  is  possible  to  cal- 
culate from  this  diagram,  also,  the  number  of  tons  required  to  be 
loaded  on  or  unloaded  from  a  vessel  in  order  to  increase  or  de- 
crease the  draft  by  I  inch,  but  the  diagram  is  not  very  con- 
veniently arranged  for  the  purpose  A  more  convenient  form  is 
the  immersion  curve. 


162 


MERCHANT  VESSELS 


5.  The  immersion  curve  is  a  curve  showing  the  displacement  per 
inch  immersion  or  emersion  at  various  drafts.  This  is  not  as 
constant  as  it  would  be  for  a  box-shaped  object,  where  the  number 
of  tons  per  inch  is  the  same  at  any  draft.  As  the  vessel  sinks  in 


FlG.    56. —  IMMERSION    CURVE 

the  water  it  requires  more  and  more  tons  to  immerse  it  another 
inch  (see  Figure  56). 


DEAD- WEIGHT  TONNAGE 

Dead-weight  tonnage  is  the  displacement  of  the  total  amount 
of  fuel,  passengers,  and  cargo  that  the  vessel  can  carry.  The 
dead-weight  tonnage  therefore  measures  the  capability  or  car- 
rying power  of  the  vessel  for  the  transportation  of  weight  cargo. 
The  capability  for  light  cargo  is  better  measured,  of  course,  by 
volume.  Dead  weight  is  carrying  power,  over  and  above  the 
actual  weight  of  the  vessel  and  equipment.  Dead  weight  is  used 
in  two  senses : 


DISPLACEMENT  AND  DEAD-WEIGHT  TONNAGE       163 

1.  Maximum  dead  weight,  or  the  carrying  power  of  the  vessel 
at  the  maximum  draft.     This  represents  the  largest  amount  of 
cargo  which  can  be  safely  carried.     It  is,  therefore,  the  difference 
between  the  "  light  displacement "  of  the  vessel  and  the  "  loaded 
displacement." 

2.  Actual  dead  weight,  or  the  carrying  power  of  the  vessel 
at  a  given  draft.     This  represents  the  amount  of  cargo  which  is 
being  carried  at  a  given  time.     It  is, -therefore,  the  difference  be- 
tween the  "  light  displacement "  of  the  vessel  and  the  "  actual  dis- 
placement." 

Measurement  of  Dead  Weight. —  i.  By  the  weight  of  water 
displaced.  This  is  done  indirectly  by  taking  the  difference  be- 
tween the  vessel  displacements,  light  and  loaded  or  light  and 
actual. 

2.  By  the  difference  in  displacements  as  described  above. 

3.  Dead-weight  scale.     It  is  customary  to  figure  out  in  advance 
the  dead-weight  capacity  at  various  drafts  and  to  combine  this  in- 
formation in  the  form  of  a  dead-weight  scale  with  the  displace- 
ment curve   (see  columns  2  and  3,  Figure  55).     If  given  sep- 
arately it  has  the  form  of  the  accompanying  diagram. 

4.  The  uses  of  these  diagrams  and  tables  in  connection  with 
dead-weight  tonnage  may  be  illustrated  as  follows : 

Suppose  the  vessel  previously  used  for  illustration  is  ready  to 
enter  a  river  port.  Her  displacement  is  15,080  tons  and  she  is 
drawing  29  feet  (in  sea  water).  The  depth  at  the  dock  in  the 
river  is  31  feet.  Can  she  enter?  This  depends  upon  how  much 
increase  in  draft  will  be  caused  by  the  change  from  sea  water 
to  fresh  water.  Since  the  weight  of  the  water  displaced  must 
equal  the  weight  of  the  vessel  and  since  sea  water  weighs  64 
pounds  to  the  cubic  foot  and  fresh  water  only  63  pounds,  it  is 
evident  that  there  will  be  some  increase  in  draft.  From  the  im- 
mersion curve  it  can  be  ascertained  that  the  number  of  tons 
per  inch  immersion  in  salt  water  at  this  draft  is  70.8.  It  will 
be  sixty-three-sixty-fourths  of  this  or  "69.69  in  fresh  water.  The 
displacement  in  sea  water  was  15,080  tons  and  the  displacement 
in  river  water  will  be  one-sixty-fourth  more,  or  235.6  tons  more. 
The  change  in  draft  will  be  235.6  divided  by  69.69,  or  3.38  inches. 
The  draft  in  fresh  water  will  be  29  feet  3.38  inches.  The  same 
idea  is  useful  in  ascertaining  that  the  vessel  when  loaded  at  the 
dock  shall  not  exceed  her  maximum  draft  when  at  sea.  Sup- 


xxx  »l 


11.9 ftt 


I.OAD  on*rr 


yyty 


XXVW 


7000 


•r 


IX 


57.— DEADWEIGHT  SCALE 


DISPLACEMENT  AND  DEAD-WEIGHT  TONNAGE       165 

pose  again  that  a  vessel  discharges  cargo,  the  weight  of  which 
is  not  known.  If  the  tons  per  inch  at  the  vessel's  draft  was  as- 
certained from  the  immersion  curve  to  be  60  and  the  draft  has 
decreased  from  29  feet  to  28^/2  feet,  the  weight  of  the  cargo  dis- 
charged must  be  approximately  six  times  60,  or  360. 

Relation  between  Displacement  and  Dead  Weight. — 
Using  other  terms,  this  might  be  stated  as  the  relation  between 
ship  displacement  and  cargo  displacement.  This  is  a  very  im- 
portant relation  in  connection  with  the  safety  of  the  vessel  and  by 
reason  of  laws  designed  to  make  ships  seaworthy  and  safe  is 
fast  becoming  a  legal  question  not  inferior  to  tonnage  in  interna- 
tional importance. 

Nature  of  the  Relation. —  The  portion  of  the  vessel  under  water 
determines  the  displacement  or  buoyancy  of  the  vessel.  But  it 
has  a  floating  power  beyond  this  or  a  reserve  buoyancy  which 
is  determined  by  the  part  which  is  not  immersed  but  may  be  made 
water-tight,  enclosed  by  the  upper  deck  and  by  the  bridge,  fore- 
castle, and  poop.  As  stated  by  White,  "  The  sum  of  the  two,  in 
short,  expresses  the  total  '  floating  power '  of  the  vessel  and  the 
ratio  of  the  part  which  is  in  reserve  to  that  utilized  is  a  matter 
requiring  the  most  careful  attention."  This  ratio  might  be  called, 
in  one  sense,  a  "  factor  of  safety."  Like  the  surplus  over  fixed 
charges  of  a  corporation,  it  enables  the  vessel  to  pull  through  diffi- 
culties. This  ratio  may  be  more  or  less  accurately  translated  into 
the  distance  between  the  water  line  and  the  height  of  the  upper 
deck,  crudely  speaking,  the  portion  of  the  hull  out  of  water,  and 
this  distance  on  the  side  of  the  vessel  when  it  is  fully  loaded 
is  called  the  minimum  "  freeboard."  The  water  line  on  the  vessel 
when  fully  loaded  is  called  the  "  load  line." 

'The  "  freeboard,"  accurately  defined,  is  the  height  of  the  side 
of  the  ship  above  the  water  line,  at  the  middle  of  the  length, 
measured  from  the  top  of  the  deck  at  the  side  or,  in  cases  where 
a  waterway  is  fitted,  from  the  curved  line  of  the  top  of  the  deck 
continued  through  to  the  side,  (see  Figure  55).'  The  free- 
board will  naturally  vary  with  the  type  and  construction  of  the 
vessel.  A  submarine,  for  example,  designed  to  operate  partially 
or  wholly  submerged,  has  no  freeboard,  while  a  passenger  vessel 
not  designed  to  carry  heavy  cargo  and  the  upper  portion  of 
which  is  lightly  constructed  will  have  considerable  freeboard. 
Fixing  the  minimum  freeboard  determines  the  maximum  loading 


i66  MERCHANT  VESSELS 

capacity,  which  the  owner  usually  desires  to  have  as  great  as  pos- 
sible. 


RULES  FOR  FREEBOARD 

In  some  types  af  vessels  the  freeboard  is  measured  to  the  main 
deck,  the  superstructures  being  light,  but  we  will  temporarily  con- 
sider the  freeboard  as  measured  to  the  upper  deck. 

1.  Old  Rules.  —  Fixing  the  minimum  freeboard  determines  the 
maximum   loading  capacity.     Originally   no  government   super- 
vision was  exercised  over  this  whatever,  so  that  greedy  vessel- 
owners  were  free,  if  they  so  desired,  to  risk  their  property  -and 
the  lives  of  sailors  in  grossly  overloaded  vessels.     Even  under 
these  conditions   there   existed   some   formulas    for   the   benefit 
of  those  who  desired  to  use  them.     The  oldest  English  rules  were 
based  upon  the  depth  of  the  vessel's  hold,  Lloyd's  rule  providing 
a  freeboard  of  from  2  to  3  inches  for  every  foot  of  depth  in  the 
hold.     This  rule  took  no  account  of  differences  in  the  form  of 
vessels  or  of  differences  in  size,  both  of  which  affected  the  work- 
ing of  the  rule.     Liverpool  underwriters  directed  surveyors  to 
make   allowance   for    form   and   strength   when   assigning   free- 
boards and  provided  graded  scales  ranging  from  2%  inches  «to  4 
inches  per  foot  depth  of  hold. 

2.  Institution  of  Naval  Architects'  Rules,  1867.  —  This  body 
devised  a  set  of  rules  with  freeboard  dependent  upon  beam.     The 
necessary  freeboard  was  calculated  at  %  of  the  beam  plus  %2 
of  the  beam  for  every  beam  in  the  length  of  the  ship  above  5 
beams.     Thus  a  vessel  with  32  feet  beam  and  224  feet  long  (7 
beams  in  the  length)   would  have  a  freeboard 


Lloyd's  rule  ignored  the  ratio  of  length  and  breadth;  this  rule 
omits  any  consideration  of  the  depth  of  the  vessel.  Deep,  nar- 
row vessels  which  would  require  exceptionally  large  freeboard 
because  of  bad  proportions  would  receive  a  smaller  freeboard 
than  a  vessel  of  equal  length  but  better  proportions.  In  present- 
day  vessels  the  freeboard  requirement  arrived  at  by  the  use  of 
a  rule  of  this  character  would  in  most  instances  be  excessive. 
This  rule  never  attained  any  general  use. 


DISPLACEMENT  AND  DEAD-WEIGHT  TONNAGE       167 

LOAD  LINE  LEGISLATION 

As  a  result  of  losses  of  vessels  at  sea  alleged  to  be  due  to  over- 
loading, many  investigations  were  made  between  1870  and  1890 
regarding  the  safety  of  vessels  at  sea.  Plimsoll  considered  that 
property  was  sacrificed  and  sailors  murdered  through  lack  of  load 
line  legislation. 

1.  Commission  of  1874.—  This  commission  reported  that  it  was 
impossible  to  lay  down  any  general  fules  on  the  subject  of  free- 
board. 

2.  Act  of  1876, —  By  act  of  Parliament  in  1875,  on  tne  s^e  °f 
vessels  in  the  foreign  trade  owners  were  required  to  have  painted 
a  mark  now  referred  to  as  the  Plimsoll  mark,  which  indicated  the 
limit  of  loading.     This  provision  was  extended  by  the  Act  of 
1876  to  apply  to  all  British  vessels  of  over  80  tons.     Official 
surveyors  had  authority   to   detain  vessels  considered  as   over- 
loaded, though  owners  might  claim  damages  if  unjustly  detained. 
These  marks,  it  will  be  noticed,  were  placed  at  the  discretion 
of  the  owners  and  really  only  served  as  a  guide  and  protection 
to  the  master  of   the  vessel.     As  was  natural   in   the  absence 
of  any  satisfactory  criterion,  many  disputes  arose  and  the  act  did 
not  accomplish  its  purpose,  except  in  a  limited  way.     Its  principal 
function  was  to  pave  the  way  for  further  legislation. 

3.  Lloyd's  Tables,   1882. —  A  committee  of  Lloyd's  Register 
of  Shipping  had  for  ten  years  been  compiling  data  relative  to 
the  loading  of  vessels  and  freeboard,  and  the  results  of  these 
investigations  were  embodied  in  the  tables  of  freeboard  issued 
in  1882.     These  took  into  account  the  structural  design  and  form 
of  the  hull  and  the  various  practices  of  loading,  and,  when  in 
1883  the  Board  of  Trade  appointed  a  committee  to  investigate 
the  possibility  of  adopting  freeboard  tables,  this  committee  urged 
the  adoption  of  the  Lloyd's  Tables  with  slight  modifications.     The 
recommendation  was  followed  by  the  Board  of  Trade.     As  a  re- 
sult a  shipowner  who  obtained  a  Lloyd's  certificate  and  had  his 
vessel  properly  marked  was  free  from  the  possibility  of  deten- 
tion for  overloading,  and  by  1890  over  2000  vessels  had  made 
voluntary  application  to  Lloyd's  for  this  purpose. 

4.  Act  of  1890. —  These  tables  were  embodied  in  the  Merchant 
Shipping  Act  of  1890  and  made  applicable  to  all  British  merchant 
vessels.     In  1906  it  was  decided  that  the  freeboard  required  for 


168  MERCHANT  VESSELS 

vessels  with  substantial  deck  erections  were  excessive  and  the 
tables  were  revised  in  this  respect,  the  reduction  varying  from 
1/2  inch  to  12  inches,  depending  upon  the  type  of  vessel.  In  1913 
a  further  investigation  was  made  by  the  Board  of  Trade  and  it 
was  decided  that  the  freeboard  tables  of  1906  were  substantially 
correct.  The  principal  work  of  this  committee  was  to  revise  the 
treatment  accorded  special  types  of  vessels,  which  had  received 
preferential  treatment.  At  the  present  time  the  owner  may  se- 
cure a  load  line  marking  from  -a  Board  of  Trade  inspection  or 
inspection  by  Lloyd's,  Bureau  Veritas,  or  British  Corporation, 
the  latter  three  classification  societies  having  been  recognized  for 
this  purpose. 

PRINCIPLES  OF  LOAD  LINE  REGULATION 

It  is  possible  to  give  a  brief  outline  of  the  factors  which  are  of 
principal  importance  in  the  fixing  of  the  maximum  load  line,  as 
illustrated  by  the  law  of  Great  Britain.  As  preliminary  thereto 
it  might  be  stated  that  there  are  two  elements  connected  with  the 
fixing  of  freeboard,  (i)  the  avoidance  of  a  loading  so  heavily 
as  to  strain  the  vessel,  and  (2)  the  maintenance  of  weatherly 
qualities.  The  latter  object  is  more  difficult  to  attain  than  the 
former,  because  of  the  many  varieties  of  vessels  and  the  diverse 
conditions  under  which  they  sail.  Its  accomplishment  involves 
sufficient  reserve  buoyancy,  decks  not  readily  swept  by  waves, 
and  good  wave-riding  qualities.  The  principal  factors  in  the 
British  tables  are : 

i.  Strength. —  The  criterion  of  strength  is  a  first-class  vessel 
according  to  Lloyd's  rules  of  1885.  The  calculated  stress  per 
square  inch  on  the  material  of  the  hull  amidships  must  not  ex- 
ceed the  calculated  stress  for  a  full-scantling  vessel  of  similar 
form  and  proportions  when  fully  loaded.  Vessels  may  have  any 
form  of  construction  but  must  meet  this  test.  A  table  is  con- 
structed in  which  various  depths  of  ships  are  listed  and  below  each 
depth  is  given  the  standard  length  for  such  depth  and  the  number 
of  inches  of  freeboard  required  for  vessels  having  this  depth  and 
various  coefficients  of  fineness.  An  illustration  of  such  a  table 
is  given  below. 

Adopting  as  an  illustration  a  flush-decked  vessel,  300  feet  long, 
38  feet  broad  and  21  feet  molded  depth,  with  a  coefficient 


DISPLACEMENT  AND  DEAD-WEIGHT  TONNAGE       169 


Depth  in  feet  .... 

20.  o 

20  < 

21.  0 

21  ? 

22  O 

27  n 

•»»%) 

^XO 

riVttroJ 

^^.o 

Length  in  feet  .  .  . 

24.O 

24.6 

2C2 

2  eg 

26/1 

•?*7n 

*.t-^\j 

^L^\J 

^j^ 

^5° 

«£UZ|. 

«V° 

in. 

• 

.66 

42.6 

44.2 

45-9 

47-6 

49-3 

SI.l 

.68 

43-2 

44-8 

46.6 

48.3 

50.0 

51.8 

.70 

43-9 

45-5 

47-3 

49.0 

50.7 

52.6 

Coefficient  of 

.72 

44-5 

46.2 

48.0 

49-7 

514 

53-3 

fineness 

74 

45-1 

46.8    „ 

48.6 

50-4 

52.1 

54-0 

.  , 

.76 

45-8 

47-5 

49-3 

5i.i 

52.8 

547 

.78 

46.4 

48.2 

50.0 

51-8 

53-5 

554 



.80 

47.1 

48.9 

50-7 

52.5 

54-3 

56.2 

of  fineness  80  per  cent  we  find  from  the  table  that  the  freeboard 
required  would  be  about  51  inches.  A  vessel  which  was  not  of 
standard  strength  would  have  the  alternatives  of  increasing  the 
structural  strength  or  having  the  tabular  freeboard  increased  until 
by  a  corresponding  reduction  of  the  load  on  the  hull  girder  the 
stress  would  be  brought  within  the  limits  of  a  standard  ship. 
Naturally,  therefore,  a  spar-decked  or  awning-decked  vessel,  which 
is  of  lighter  construction  than  a  full-scantling  vessel,  would  have 
a  greater  freeboard  than  the  latter.  This  is  taken  care  of  by  sep- 
arately providing  for  these  types  of  vessels  in  the  tables.  No  re- 
duction in  freeboard  is  given,  however,  for  a  vessel  of  greater 
structural  strength  than  the  standard,  because,  as  previously  stated, 
weatherly  qualities  must  be  considered  and  if  strength  alone  were 
a  criterion  it  would  be  possible  to  build  a  vessel  for  which  no  free- 
board was  necessary. 

2.  Reserve  Buoyancy. —  Reserve  buoyancy  enables  the  vessel 
to  rise  smartly  when  among  waves  and  therefore  is  necessary  in 
some  degree  to  all  seagoing  merchant  vessels.  Otherwise  waves 
would  continually  sweep  the  decks,  with  the  possibility  of  water 
entering  the  ship.  The  reserve  buoyancy  is  principally  dependent 
upon  (a)  the  sheer  and  (&)  superstructures.  If  the  ship  has  suf- 
ficient sheer  the  ends  are  more  buoyant  and  the  stem  and  stern 
less  likely  to  be  swamped  by  oncoming  and  following  waves.  A 
flush-decked  vessel,  without  sheer,  and  loaded  to  the  gunwales 
would  have  no  reserve  buoyancy,  would  not  lift  with  the  waves, 
would  float  nearly  submerged  if  the  upper  deck  was  water-tight, 
and  would  be  continually  washed  by  the  waves.  The  wave-riding 
qualities  are  not  measured  solely  by  the  absolute  volume  of  reserve 


i;o         •  MERCHANT  VESSELS 

buoyancy  but  by  the  proportion  which  it  bears  to  the  vessel's  dis- 
placement, because  if  not  of  sufficient  proportion,  while  the  vessel 
would  rise  it  would  not  rise  quickly  enough.  Suppose,  therefore, 
that  the  vessel  used  above  as  an  illustration  has  a  sheer  forward  of 
8  feet  and  a  sheer  aft  of  3  feet  or  a  mean  sheer  of  66  inches.  Ac- 
cording to  the  rules,  the  mean  sheer  for  a  standard  vessel  is  Mo 
of  the  length  in  feet  plus  10.  For  a  vessel  300  feet  long  the  sheer 
would  be  YIQ  of  300  plus  10  or  40  inches.  This  vessel,  however, 
has  a  sheer  of  66  inches  or  a  surplus  of  26  inches.  Only  .5  of  the 
standard  is  allowed  as  excess,  however,  so  that  the  excess  is  con- 
sidered as  20  inches.  One-fourth  of  this  excess,  or  5  inches,  is 
allowed  by  the  rules  as  a  deduction  from  the  freeboard,  thus  re- 
ducing the  freeboard  from  51  inches  to  46  inches. 

3.  Form. —  It  should  be  noted  that  the  freeboard  for  a  large 
vessel  must  be  greater  in  proportion  to  depth  than  for  a  small 
vessel  inasmuch  as  several  waves  may  be  acting  on  the  length  at 
the  same  time.  Thus  the  top  of  a  small  plank  may  remain  per- 
fectly dry,  rising  with  each  wave,  while  the  top  of  a  long  plank 
will  be  wetted  because  each  portion  of  the  length  is  submerged  as  a 
small  wave  passes.  The  length  of  the  hull  is,  therefore,  an  im- 
portant factor  in  freeboard.  The  standard  relation  of  length  to 
depth  is  12  to  i.  The  vessel  used  as  an  illustration  has  a  length 
of  300  feet  and  a  depth  of  21  feet.  Since  its  length  is  more  than 
12  times  the  depth  an  allowance  for  this  must  be  made  in  free- 
board. For  each  10  feet  of  additional  length  a  correction  of  i.a 
feet  must  be  added  to  the  freeboard  (this  correction  being  a  frac- 
tion of  the  length  plus  a  constant,  ascertained  from  the  rules). 
The  length  of  this  vessel  exceeds  the  standard  length  for  the  given 
depth  by  48  feet.  The  correction  would,  therefore,  be  4%0  X 
1.2,  or  5%  inches,  which  added  to  the  freeboard  already  calcu- 
lated (46  inches)  would  give  51.75  inches  as  the  winter  free- 
board. From  this  is  deducted  so  many  inches  per  foot  of  draft 
to  arrive  at  the  summer  freeboard. 

In  connection  with  form  it  will  also  be  noticed  that  by  means  of 
the  coefficients  of  fineness  in  the  table  on  page  169  a  greater  free- 
board is  required  for  a  full  than  a  fine  vessel.  Other  things  be- 
ing equal,  the  full  vessel  is  less  lively  than  the  vessel  with  finer 
lines. 


DISPLACEMENT  AND  DEAD-WEIGHT  TONNAGE       171 

4.  Deck  Erections. —  We  have  previously  stated  that  deck  erec- 
tions are  an  important  factor  in  reserve  buoyancy.     The  fore- 
castle and  poop,  for  example,  serve  the  same  purpose  as  sheer  in 
making  the  ends  of  the  vessel  lively.     The  forecastle  is  the  most 
important  deck  erection  for  its  length,  because  it  adds  buoyancy 
where  it  is  most  effective,  raising  the  bow  to  meet  the  waves  and 
minimizing  the  effect  of  head  seas.     A  poop  performs  the  same 
function  at  the  stern.     The  bridge  raises  the  working  platform  out 
of  water  and  covers  the  machinery  openings.     Deck  erections,  i$ 
order  of  value  from  freeboard  standpoint,  are  listed  as  follows : 

a.  Continuous  end-to-end  erection  forming  awning  deck  of  an 

awning-decked  vessel. 

b.  Erection  in  the  form  of  a  shelter  deck.* 

c.  Well-decked  vessel  or  forecastle,  bridge  and  poop,  varying 

according  to  completeness  and  continuousness. 

The  length  and  completeness  of  closure  evidently  determine 
the  effectiveness  of  the  erections.  The  shelter  deck  with  tonnage 
openings  can  never  be  better  than  the  awning  deck  nor  can  a 
forecastle,  bridge  and  poop  covering  three-fourths  of  the  length 
be  superior  to  a  shelter  deck,  using  this  term  in  the  sense  now 
employed.  Suppose,  therefore,  that  the  vessel  previously  used 
for  illustration  has  a  poop  50  feet  long,  a  bridge  60  feet  long,  and 
a  forecastle  25  feet  long.  The  combined  erections  cover  45  per 
cent  of  its  length.  The  tables  give  the  allowance  to  be  made  for  a 
complete  superstructure  (say  32  inches),  and  for  one  covering 
only  45  per  cent  of  the  length  allow  one-fourth  of  the  deduction 
for  a  complete  superstructure.  The  allowance  in  this  case  would, 
therefore,  be,  say,  8  inches.  The  flush-decked  vessel's  freeboard 
would  consequently  be  reduced  by  the  deck  erections  from  51.75 
inches  to  43.75  inches. 

5.  Side  Openings. —  There  may  be  exceptions  to  the  above 
rules  in  the  case  of  vessels  whose  side  openings  prevent  the  as- 
signment of  a  load  line  as  high  as  that  calculated  by  the  tables. 

6.  Variance  of  Load  Line. —  The  load  line  must  necessarily 
vary  with  the  season  of  the  year  and  the  nature  of  the  voyage. 
Accordingly,  we  find  the  following  freeboards  marked : 

a.  Fresh  water  freeboard  is  the  minimum  freeboard  permitted 
in  summer  when  vessels  are  loaded  in  fresh  water.  The  difference 


172  MERCHANT  VESSELS 

between  the  summer  fresh  water  freeboard  and  the  summer  salt 
water  freeboard  is  the  allowance  to  be  made  for  loading  in  fresh 
water  at  other  seasons  of  the  year. 

b.  Indian  summer  freeboard  is  the  minimum  freeboard  per- 
mitted in  salt  water  for  voyages  in  the  Indian  Seas,  between  the 
limits  of  Suez  and  Singapore,  during  the  fine  season. 


Fw. 

e 


FlG.   58. —  FREEBOARD   MARKS 

c.  North  Atlantic  winter  freeboard  is  the  minimum  freeboard 
permitted  in  salt  water  for  voyages  from,  or  to,  European  or  Med- 
iterranean ports  to,  or  from,  North  American  ports  situated  north 
of  Cape  Hatteras,  between  the  months  of  October  and  March,  in- 
clusive. 

d.  Winter  freeboard  is  the  minimum  freeboard  permitted  in 
salt  water  for  voyages  from  European  or  Mediterranean  ports 
between  the  months  of  October  and  March,  inclusive,  and  for  . 
voyages  in  other  parts  of  the  world  during  the  recognized  winter 
months,  subject  to  the  exception  provided  in   (c}  above. " 

e.  Summer  freeboard  is  the  minimum  freeboard  permitted  in  K 
salt  water  for  voyages  from  European  or  Mediterranean  ports, 
between  the  months  of  April  and  September,  inclusive,  and  for 
voyages  in  other  parts  of  the  world  during  the  recognized  summer 
months,  subject  to  the  exception  provided  for  in  (b)  above. 

PROPOSED  REVISION  OF  1916 

A  committee  appointed  by  the  Board  of  Trade  in  1913  reported 
to  Parliament  in  1916  that  the  freeboards  assigned  by  the  rules 
were  apparently  satisfactory  so  far  as  safety  was  concerned  and 
had  not  contributed  to  losses  at  sea.  They  recommended  a  re- 
vision of  the  rules,  however,  to  eliminate  preferential  treatment 


DISPLACEMENT  AND  DEAD-WEIGHT  TONNAGE       173 

of  types  of  vessels  not  satisfactorily  covered  by  the  old  rules^ 
The  principal  changes  recommended  were  the  following: 

1.  The  existing  rules  tabulate  the  winter  freeboards  while  the 
proposed  rules  tabulate  the  summer   freeboards  with  additions 
for  winter. 

2.  Existing  rules  classify  steamers  according  to  the  extent  and 
disposition   of  their  superstructures  —  to   some  extent  an  arbi- 
trary classification  with  some  classes  merging  into  others  —  and, 
as  the  deduction  is  different  in  each  class,  this  results  in  some 
anomalies.     The  proposed  rules  introduce  a  '*  type  factor,"  sep- 
arate factors  being  assigned  to  vessels  of  different  types  and  the 
allowance  for  superstructures  being  the  result  of  the  formula 
F  X  R  X  D,F  being  the  type  factor,  R  the  ratio  of  superstruc- 
ture length  to  total  length,  and  D  the  reduction  given  for  complete 
superstructures. 

3.  In  the  proposed  rules  two  standards  for  sheer  are  proposed, 
one  for  vessels  with  forecastles  and  a  higher  standard  for  those 
without.     In  the  existing  rules  an  allowance  is  made  for  an  excess 
of  sheer  in  flush-decked  vessels  but  no  such  reduction  is  allowed 
in  the  proposed  rules. 

4.  The  correction  for  the  ratio  of  length  to  depth  has  been 
embodied  in  the  proposed  rules  as  a  function  of  the  length,  the 
increase  or  decrease  in  freeboard  being 

(.0003  L  +  .05)   (L  —  I2D) 

L  being  the  length  and  D  the  freeboard  depth  of  the  vessel  in  feet. 
The  standard  ratio  is  retained  as  12  to  i,  except  that  when  the 
ratio  of  length  to  depth  exceeds  15,  the  freeboard  shall  be  com- 
puted as  if  the  ratio  were  15. 

5.  Holms,  who  was  a  member  of  the  committee,  expresses  his 
opinion  as  to  the  effect  of  the  changes  on  existing  freeboards  as 
follows : 

The  freeboards  given  by  the  rules  formulated  by  this  committee 
vary  very  little,  in  the  majority  of  vessels,  from  those  given  under 
the  old  rules;  any  difference  there  may  be  being  due  principally  to 
the  avoidance  of  special  treatment  of  certain  types  of  vessels,  and  to 
a  reduction  in  the  allowance  made  for  superstructures  the  means  of 
closing  the  openings  in  the  terminal  bulkheads  of  which  are  not  up 
to  a  certain  standard.  Compared  with  the  old  rules,  the  new  are  easy 
to  apply  and  are  simple  and  accurate. 


i?4  MERCHANT  VESSELS 

UNITED  STATES  LEGISLATION 

An  act  of  1891  provided  that  "  the  owner,  agent,  or  master  of 
every  inspected  seagoing:  steam  or  sail  vessel  shall  indicate  the 
draft  of  water  at  which  he  shall  deem  his  vessel  safe  to  be  loaded 
for  the  trade  she  is  engaged  in,  which  limit  as  indicated  shall  be 
stated  in  the  vessel's  certificate  of  inspection,  and  it  shall  be  un- 
lawful for  such  vessel  to  be  loaded  deeper  than  stated  in  said 
certificate."  As  stated  by  the  Commissioner  of  Navigation,  the 
effect  of  this  was  to  place  more  scrupulous  owners  at  a  commercial 
disadvantage,  and  the  law  was  repealed  in  1897.  At  the  present 
time  no  load  line  legislation  exists.  In  1916  a  conference  was 
held  between  the  Secretary  of  Commerce,  shipbuilders,  shipowners, 
and  representatives  of  classification  societies,  and  the  matter  was 
referred  to  a  committee  for  recommendations.  A  bill  is  now  pend- 
ing in  Congress  requiring  load  line  regulation,  providing  for  a 
load  line  to  be  marked  on  vessels  as  the  Secretary  of  Commerce 
may  suggest,  and  for  the  recognition  of  substantially  similar  for- 
eign laws.  As  was  the  case  with  tonnage  measurement,  foreign 
nations  followed  the  example  of  Great  Britain,  and  Germany, 
France,  Holland,  and  other  maritime  nations  passed  similar  laws. 
Numerous  experts  have  testified  to  the  necessity  of  an  established 
load  line  but  vessel  owners  have  always  feared  it  would  operate 
prejudicially  to  certain  trades  or  types  of  carriers.  The  most 
effective  method  of  dealing  with  this  subject  would  be  through  an 
international  conference  which  would  make  common  regulations 
for  all  nations.  Each  nation  is,  of  course,  reluctant  to  pass  load 
line  laws  which  will  hamper  its  merchant  marine  in  competition 
with  foreign  vessels.  The  International  Conference  on  Safety  at 
Sea  which  met  during  the  World  War  considered  this  question, 
but  the  matter  was  deferred  until  the  close  of  hostilities.  The 
subject  will  be  a  prominent  one  at  the  next  conference. 

REFERENCES 

i.  JOHNSON,  E.  R. :  Report  on  Panama  Canal  Traffic  and  Tolls. 
Washington,  1913.  Chap.  III.  (A  brief  discussion  of  the 
nature  of  displacement  and  dead-weight  tonnage  and  extended 
consideration  of  its  desirability  as  a  basis  for  canal  tolls.) 


DISPLACEMENT  AND  DEAD-WEIGHT  TONNAGE       175 

2.  HOLMS,    A.    C. :    Practical   Shipbuilding.    Longmans,    Green    & 

Co.,  London  and  New  York,  1916.  Chap.  VII.  (Extensive 
discussion  of  the  factors  influencing  the  regulation  of  load 
lines,  history  of  English  legislation,  description  of  the  recom- 
mendations of  the  Committee  of  1916.) 

3.  WALTON,    THOMAS  :    Know    Your   Own    Ship.     Griffin    &    Co., 

London,  1917.  Chap.  I.  (A  good  discussion  of  displacement 
and  dead- weight  tonnage  and  their  calculation.)  Chap  IX. 
(A  good  discussion  of  present  British  regulation  of  the  load 
line.) 

4.  WHITE,  W.  H. :  Manual  of  Naval  Architecture.  Murray,  Lon- 
don, 1894.  Chap.  I.  (Good  description  of  displacement  ton- 
nage and  of  British  load  line  legislation  up  to  1890.) 

5.  "  Report  of   Board  of  Trade   Committee   to   Parliament,   Great 

Britain,  1916."  In  "  Report  of  Commissioners,  etc.,"  1916. 
Vol.  X,  Cd.  8204.  (Brief  history  of  British  laws  and  proposed 
revised  rules  and  tables  of  freeboard.) 

6.  "  Reports  of  Commissioner  of  Navigation,  United  States,  1915, 

1916,  1919."  (Notes  of  progress  in  load  line  legislation  in 
United  States.) 

7.  Conference  on  Establishment  of  Load  Line  Regulations,  Dept. 

of  Commerce  and  Labor,  United  States.  Washington,  1916. 


CHAPTER  X 

GROSS  TONNAGE 

DEFINITION 

Gross  tonnage  is  an  attempt  to  express,  in  units  of  100  cubic 

>         feet,  the  internal  cubical  capacity  of  a  vessel,  in  other  words,  its 

/*       volume.     If  a  vessel  were  a  parallelopipedon  (a  six-sided  object 

'\  /•  with  opposite  sides  parallel  and  equal  to  each  other)  the  volume 

\  /j    would  be  measured  by  the  product  of  the  length,  breadth,  and 

depth,  and  would  be  expressed  in  tons  of  100  cubic  feet  by  dividing 

by  100.     It  is  evident  that  the  volume  of  a  vessel  will  be  depend- 

ent upon  these  three  factors,  but  being  rounded  off  toward  the 

keel  and  sharpened  at  the  ends  its  sides  are  not  parallel  and  con- 

sequently it  has  a  volume  considerably  less  than  the  product  of  its 

greatest  length,  breadth,  and  depth.     In  the  early  rules  attempts 

were  made  to  estimate  the  space  in  a  vessel  by  the  product  of  these 

three  factors  modified  by  some  divisor  intended  to  deduct  a  frac- 

tion of  the  result  obtained  to  allow  for  such  rounding  off.     Thus, 

in  a  book  published  in  1711  "two  good  old  rules"  are  quoted, 

one  being 


L  (length)  X#  (breadth)  X  #  (depth) 
,  -  —  gross  tonnage 
95 

Similarly  the  first  tonnage  law  in  England   (1694)   prescribed 
the  rule 


=  gross  tonnage 


94 


Such  rules  could  apply  equitably  to  all  vessels  only  if  there  were 
a  uniform  degree  of  rounding  off  toward  the  keel,  stem,  and 
stern,  which  was  decreasingly  true  as  ships  became  more  varied 
and  intricate  in-  design.  If  the  factor  of  94  was  correct  for  the 
"  full  "  ship  it  was  palpably  unjust  to  the  vessel  with  finer  lines 

176 


GROSS  TONNAGE  177 

or  vice  versa.  Furthermore,  the  rule  is  so  simple  that  as  soon. 
as  incentive  appeared  in  the  form  of  duties  based  on  registered 
.tonnage  it  was  easy  for  enterprising  shipowners  and  builders  to 
construct  vessels  designed  to  evade  the  rule.  For  example,  when 
it  was  assumed  that  the  depth  of  a  vessel  bore  a  fixed  relation  to 
its  breadth  of  i  to  2  and  the  rule  was  modified  in  England  (1720) 
to 

L  X  B  X  l/2  B 

-  =  gross  tonnage, 
94 

vessel  depths  grew  surprisingly  in  comparison  with  breadths. 
Ships  became  deep  and  unseaworthy  boxes,  because  this  increased 
the  carrying  capacity  without  ,  affecting  the  legal  tonnage.  Full- 
ness of  lines  had  a  similar  effect. 

The  definition  shows  gross  tonnage  to  be  a  measure  of  the 
volume  of  a  vessel.  But  since  it  is  not  a  mere  exercise  in  mensura- 
tion and  has  a  purpose,  this  definition  must  be  somewhat  modi- 
fied to  bring  it  in  accord  with  the  purpose  of  approximately  stating 
the  gross  volume  in  order  to  derive  therefrom  the  "  carrying  ca- 
pacity "  in  terms  of  space  unit.  All  the  space  is  not  measured  at 
present,  therefore,  some  portions  not  being  available  as  pas- 
senger or  cargo  spaces.  Such  space  might  be  deducted  from  the 
gross  tonnage  in  order  to  find  the  earning  capacity  or  might  be 
omitted  from  measurement;  both  methods  are  in  fact  employed. 
The  definition  might  properly  read,  therefore,  "  gross  tonnage  is 
an  attempt  to  express  an  understood  part  of  the  internal  cubical 
capacity." 

•  j  t  , 
GENERAL  NATURE 

Gross  tonnage  is  the  product  of  centuries  of  development  in 
various  countries  and  the  result  is  a  diversity  of  methods  as  illogi- 
cal as  it  is  unjust.  As  is  the  case  with  many  commercial  usages, 
custom  and  precedent  have  prevented  the  adoption  of  a  uniform 
standard  which  would  be  beneficial  to  all.  The  earliest  rule  was 


=  gross  tonnage 


100 
This  was  manifestly  incorrect  as  the  vessel  had  curved  and  not 


178  MERCHANT  VESSELS 

straight  sides.  It  better  measured,  proportionately,  however,  the 
respective  volume  of  individual  vessels  than  some  later  rules. 
This  was  followed  by  the  introduction  of  a  divisor,  the  rule  being 


,  or 


94  95 

a  refinement  of  the  same  principle.  On  the  assumption  of  a 
fixed  relation  between  breadth  and  depth,  and  to  facilitate  the 
measurement  of  vessels  loaded  and  afloat  the  rule  was  amended  to 


(L-3/s 
and  to 


94 

in  order  to  allow  for  rake  and  round  of  stem  and  stern.  Such  a 
rule,  with  a  divisor  of  95,  existed  in  the  United  States  until  the 
adoption  of  the  Moorsom  system.  Internal  measurements  have 
uniformly  been  used,  although  a  system  based  on  outside  meas- 
urements was  proposed  by  the  English  Commission  of  1849.  Im- 
proved mensuration  showed,  however,  that  the  internal  volume 
could  be  more  accurately  found  by  Simpson's  rule  for  ascertaining 
plane  areas  bounded  by  parabolic  curves,  and  this  was  the  basis 
for  all  national  measurements  after  1854. 

Early  rules  and  early  laws  often  adopted  total  gross  tonnage 
as  a  basis  of  measurement,  but  later  it  became  customary  to 
exempt  from  measurement  certain  spaces.  Thus  allowance  was 
made  for  the  rake  of  stem  and  stern,  divisors  were  modified  to 
obtain  desired  reductions  in  tonnage,  allowances  were  made  for 
engine-room  space  and  space  used  for  storage  of  sails,  spaces  not 
"  permanently  closed  in  "  were  exempted  and  also  spaces  devoted 
to  the  use  of  the  crew.  The  effect  of  these  will  be  seen  later  as 
we  encounter  them  in  the  process  of  measurement.  It  is  sufficient 
to  say  that  in  the  present  United  States  rules  water-ballast  space. 
spaces  not  "  permanently  closed  in,"  passenger  accommodations, 
hatchways,  spaces  connected  with  the  operation  of  the  vessel 
and  for  the  use  of  the  crew  are  wholly  or  partially  exempt  from 
measurement. 


GROSS  TONNAGE  179 

DIVISIONS  IN  THE  MEASUREMENT  OF  GROSS  TONNAGE 

Before  proceeding  to  the  process  of  measurement  it  will  be  con- 
ducive to  clearness  to  point  out  that  it  contains  some  well-marked 
subdivisions.  The  gross  tonnage  is  the  sum  of  the  following 
items : 

1.  Under-deck  Tonnage. —  The  capacity  of  the  vessel  below 
the  tonnage  deck. 

2.  'Tween-deck  Tonnage. —  The  capacity  of  the  spaces  between 
the  decks  above  the  tonnage  deck.     The  capacity  between  the 
second  and  upper  deck  and  between  the  upper  and  shelter  decks 
in  a  vessel  with  three  decks  and  a  shelter  deck. 

3.  Superstructures. —  The  capacity  of  "  closed-in  "  structures 
above-deck,    including    forecastle,    bridge,    poop,    deck    houses, 
chart  houses,  "  closed  "  shelter  decks,  etc. 

4.  Hatchways. —  The  capacity  of  hatchways  in  so.  far  as  it 
exceeds  ^  of  i  per  cent  of  the  gross  tonnage. 

It  is  also  necessary  to  note  the  three  ways  in  which  spaces  are 
treated  in  the  measurement  process.  According  to  method  spaces 
may  be  classified  as  follows : 

1.  Included  Space. —  A  space  which  is  measured  in  calculating 
gross  tonnage.     For  example,  the  space  under  the  tonnage  deck 
and  'tween-deck  spaces.  .  It  may  be  deducted  later,  as  for  example, 
the  allowance  for  propelling  space. 

2.  Exempted   Space. — A   space   not  measured   in   calculating 
gross  tonnage.     For  example,  the  wheel  house  and  "  open  "  shelter 
decks. 

3.  Deducted  Space. —  A  space  included  in  the  calculation  of 
gross  tonnage  and  later  deducted  from  same.     The  deduction  is 
sometimes  limited  to  less  than  the  space  originally  included,  for 
instance,  allowance  for  crew  space. 

PROCESS  OF  MEASUREMENT  UNDER  UNITED  STATES  RULES 

i.  The  Tonnage  Deck. —  The  tonnage  deck  is  the  upper  deck 
in  vessels  with  less  than  three  decks.  In  vessels  with  three  decks 
or  more  it  is  the  second  deck  from  below.  In  three-deck  vessels 
the  lower  deck  is  often  omitted  and  there  is  merely  space  for  the 
same  so  that  the  first  actual  deck  becomes  the  "  tonnage  "  deck. 
The  American  rules  state  "  In  all  other  cases  "  (other  than  ves- 


i8o  MERCHANT  VESSELS 

sels  with  three  or  more  decks)  "  the  upper  deck  of  the  hull  is 
to  be  the  tonnage  deck."  In  a  two-deck  vessel  a  spar  or  awning 
deck  apparently  might  conceivably  be  the  tonnage  deck,  but  this 
is  not  of  much  practical  importance. 

2.  Length. —  The   length   for  tonnage   purposes  is   measured 
along  the  upper  side  of  the  tonnage  deck  from  stem  to  stern. 
By  stem  is  meant  the  inside  of  the  inner  plank  at  the  side  of  the 
stem  and  by  stern  the  inside  of  the  plank  on  the  stern  timbers. 
In  making  this  measurement,  since  the  distances  are  actually  taken 
slightly  above  the  prescribed  place,  allowance  must  be  made  for 
the  rake  of  the  stem  and  stern  through  the  thickness  of  the  deck 
and  the  rake  of  the  stern  through  one-third  of  the  round  of  the 
beam.     The  tonnage  length  is  shown  in  the  diagram  by  the  line 
AB  and  it  will  be  noted  that  the  tonnage  length  differs  from  the 
register  length,  which  is  measured  from  the   fore  part  of  the 
outer  planking  on  the  side  of  the  stem  to  the  after  part  of  the 
main    sternpost.     The   English   "  New   Measurement "    rules   of 
1835  took  the  tonnage  length  at  half  the  midship  depth  from  the 
after  side  of  the  stem  to  the  fore  side  of  the  sternpost  but  in 
recent  years  the  tonnage  length  has  never  been  the  subject  of  much 
discussion  and  is  similarly  measured  under  the  rules  of  France, 
England,  and  Germany. 

3.  Divisions  of  Length. —  The  tonnage  length  having  been  as- 
certained, the  vessel  is  divided  into  sections  for  the  purpose  of 
measurement;  the  greater  the  length  the  greater  the  number  of 
sections  required,  for  the  curves  of  a  vessel's  sides  will  vary  with 
its  length,  and  other  things  being  equal,  the  greater  the  number 
of  subdivisions  the  more  accurate  the  measurement.     The  ton- 
nage length  is  to  be  marked  off  in  equal  parts,  the  number  of 
equal  parts  for  vessels  of  various  lengths  being  as  follows : 

Tonnage  length  f 

(feet)  Equal  parts 

50  or  under   6 

51  to  100  8 

101  to  150 10 

151    tO   200    12 

2OI    tO   250    14 

251  and  over 16 

At  each  of  the  points  of  division  so  ascertained  the  area  of  a 
transverse  section  is  to  be  found.     This  system  is  also  followed  in 


GROSS  TONNAGE  181 

France,  England,  and  Germany,  though  the  number  of  divisions 
vary  in  these  countries.  The  divisions  for  a  vessel  of  over  250 
feet  are  indicated  as  Ci,  C2,  C3,  etc.,  on  Diagrams  60  and  62. 

4.  The  Area  of  Transverse  Sections. —  The  object  of  dividing 
the  tonnage  length  was  to  mark  a  number  of  points  at  which  to 
measure  the  area  of  transverse  vertical  sections.  The  areas  of 
these  sections  depend  upon  the  depth  of  the  ship,  which  is  not 

V 

bf-. r 


FlG.    59.  —  TONNAGE  LENGTH 

necessarily  the  same  throughout  the  length  of  the  vessel,  and 
upon  the  breadth  of  the  ship,  which  diminishes  as  the  vessel  rounds 
off  toward  the  keel.  Several  depths  and  breadths  must  be 
measured,  therefore,  and  this  justifies  the  division  of  length  re- 
ferred to  above.  At  each  of  the  points  of  division  (Ci,  C2/etc., 
on  Diagrams  60  and  62)  the  depth  of  the  vessel  is  measured  by  a 
measuring  stanchion  consisting  of  two  rods  attached  to  each  other 
so  that  their  united  length  may  be  increased  or  decreased.  Such 
depths  are  indicated  by  the  lines  CD  on  Diagram  60.  These  depths 
are  measured  from  a  point  at  a  distance  of  one-third  of  the  round 


FlG.   60.  —  DIVISION    OF  TONNAGE  LENGTH    AND   DEPTHS 

of  the  beam  below  the  deck  to  the  upper  side  of  the  floor  timber. 
The  round  of  the  beam  may  be  ascertained  by  stretching  a  line 
across  the  deck  from  side  to  side  at  equal  height  from  the  deck  on 
each  side  so  as  just  to  touch  the  crown  of  the  deck  at  the  middle 
line  (see  Diagram  61).  In  steel  ships  floor  plates  are  found  in- 
stead of  floor  timbers,  and  in  vessels  with  double  bottoms  the 
measurement  is  made  to  the  inner  plate  of  the  double  bottom  so 
that  the  space  for  water  ballast  is  not  measured,  provided  it  is 


182 


MERCHANT  VESSELS 


not  available  for  the  carriage  of  cargo,  stores,  supplies,  or  fuel. 
In  oil-burning  vessels  it  is,  of  course,  usually  available  for  fuel. 
The  average  thickness  of  the  ceiling  is  deducted.  One  of  the 
depths  so  arrived  at  is  indicated  by  the  line  CD  in  Diagram  61. 
Then  if  the  depth  at  the  middle  division  of  the  tonnage  length 
does  not  exceed  16  feet  divide  each  depth  into  4  equal  parts,  and  if 
said  depth  does  exceed  16  feet  divide  each  depth  into  6  equal 
parts.  These  points  of  division  are  marked  E,  F,  G,  H,  I,  J  and 
K  on  Diagram  61,  and  at  each  of  said  points  the  breadth  of  the 
vessel  is  to  be  measured,  giving  the  lines  marked  LM,  NO,  PQ, 


FlG.  6l. —  MEASUREMENTS   OF  TRANSVERSE   SECTION 

RS,  TU  and  VW,  on  Diagrams  61  and  62.  We  now  have  the  data 
necessary  to  ascertain  the  area  of  the  vertical  transverse  section 
at  each  point  of  division  of  the  tonnage  length,  Ci,  C2,  C3, 
etc.  This  is  accomplished  by  the  use  of  Simpson's  rule,  which 
will  be  next  described. 

5.  Simpson's  Rule. —  Divide  the  base  into  an  even  number  of 
equal  parts.  Through  the  points  of  division  and  at  the  extremities 
draw  ordinates  to  the  curve  perpendicular  to  the  base  and  measure 
their  lengths.  These  ordinates  will  consequently  be  odd  in 
number.  Multiply  the  length  of  each  of  the  even  ordinates  by 
4,  and  each  of  the  odd  ordinates  by  2,  excepting  the  first  and 
last,  which  multiply  by  I.  The  sum  of  these  products  multiplied 
by  one-third  of  the  common  interval  between  the  ordinates  will 
give  the  required  area.  r  In  the  vertical  transverse  section  at 


GROSS  TONNAGE 


183 


each  division  point  in  the  tonnage  length  of  the  vessel  we  have 
an  area  which  may  be  measured  by  the  foregoing  rule  with  ap- 
proximate correctness.  The  ordinates  referred  to  are  the  breadths 
of  the  vessel  measured  at  different  depths  and  the  depth  is  the 
"  base  "  referred  to.  Suppose  we  take  a  midship  transverse  sec- 
tion for  illustration  and  find  it  to  have  the  dimensions  indicated 


FlG.   62. —  TRANSVERSE   SECTIONS 

in  Diagram  62.  The  breadths  are  numbered  I,  2,  3,  4,  5,  6,  and  7, 
starting  from  above  and  these  breadths  are,  respectively,  48,  48, 
49,  48,  48,  47,  and  36  feet.  Multiplying  the  even-numbered 

Breadth    Multiplier    Product 
(feet) 


48 
48 

49 
48 

48 
47 


X 

X 
X 
X 
X 
X 


36     X 


48 
192 

98 
192 

96 
188 
J6 

850 


184  MERCHANT  VESSELS 

9 

breadths  by  4  and  the  odd-numbered  breadths  by  2,  except  the 
ist  and  7th,  we  obtain  the  results  stated  above. 

The  depth  of  the  midship  section  was  16.5  feet  which  was 
,  *^/y1  divided  into  6  parts,  giving  a  common  interval  betwen  divisiqn 
points  of  ^4$  f^et.     One-third  of  this  common  interval  is-J^f 

/>*]5  <f>  AfL. 

Therefore,^  X  850^  if&iso  square  feet. 

This  is  the  area  of  the  midship  vertical  transverse  section.  In 
the  vessel  in  question,  having  a  length  of  over  250  feet,  there 
are  17  division  points  on  the  tonnage  length  and  consequently  15 
such  sectional  areas  to  be  measured,  but  the  calculation  is  exactly 
the  same  for  each  as  the  above. 

6.  Calculation  of  Principal  Volume. —  Let  us  assume  that  the 
vertical  transverse  sections,  as  measured  by  the  foregoing  method, 
show  areas  as  follows,  reading  from  stem  to  stern: 

Section        Area  in  sq.  ft. 
Ci  o 

€4  890 

C5  1000 

C6  1080 

€7  i 120 

C8  1160 

€9  1160 

Cio  1080 

Cu  looo 

Ci2  900 

750 

575 

400 

Ci6  200 

€17  o 

These  areas  are  numbered  from  i  up,  from  stem  to  stern,  and 
Simpson's  rule  is  again  applied.  The  ist  and  I7th  areas  are 
multiplied  by  i,  every  other  odd-numbered  area  by  2  and  every 
even-numbered  area  by  4,  giving  the  result  in  the  table  below. 

The  length  of  the  vessel  may  be  assumed  to  be  400  feet,  and  its 
division  into  16  equal  parts  makes  the  common  interval  between 
the  division  points  25  feet.  One-third  of  this  common  interval 
is  8%  feet.  Multiplying  the  product  obtained  above  by  one-third 
of  the  common  interval  we  get 

Sl/s  X  37>28o  =  310,542  cubic  feet 


GROSS  TONNAGE 


185 


Section 

Area 

Multiplier 

Product 

Ci 

0 

I 

o 

C2 

380 

4 

1520 

C3 

680 

2 

1360 

C4 

890 

4 

356o 

C5 

IOOO 

2 

2OOO 

C6 

1080 

4 

4320 

C7 

II2O 

2 

2240 

C8 

1160 

4 

4640 

C9 

1160 

2 

2320 

Cio 

1080 

4 

4320 

Cn 

IOOO 

2 

2OOO 

Cl2 

900 

4 

3600 

Ci3 

750 

2 

1500 

Ci4 

575 

4 

2300 

Ci5 

400 

2 

800 

Ci6 

200 

4 

800 

Ci7 

o 

I 

o 

37280 

as  the  principal  volume  of  the  vessel.  Since  the  Moorsom  ton 
is  equivalent  to  100  cubic  feet  of  space,  the  tonnage  under  the 
tonnage  deck  of  this  vessel  is  about  3105.-  This  is  the  register 
tonnage  of  the  vessel  subject  to  certain  later  additions  and  deduc- 
tions, which  in  this  particular  vessel*  are  extensive. 

7.  Between-deck  Tonnage. —  While  the  rules  of  various  na- 
tions are  substantially  similar  for  the  calculation  of  the  tonnage 
below  the  tonnage  deck,  so  that  such  tonnage  is  practically  identical 
by  all  systems  of  measurement,  the  rules  for  calculating  'tween- 
deck  tonnage  differ  considerably. 

At  this  point  it  is  necessary  to  notice  the  discrepancy  in  measure- 
ment which  has  arisen  from  the  different  interpretations  placed 
upon  the  expression  "  permanently  closed  in  "  and  similar  phrases, 
a  discrepancy  as  great  as  that  occasioned  by  any  other  feature  of 
measurement.  The  Moorsom  Act  of  1854  in  Great  Britain  pro- 
Vided  for  the  measurement  of  "  permanent  closed-in  spaces,"  and 
these  were  uniformly  measured  until  by  1860  vessel-owners  were 
clamoring  for  the  exemption  of  various  kinds  of  superstructures 
and  the  space  under  what  is  now  known  as  a  "  shelter  deck." 
The  decision  in  England  in  the  Bear  case  in  1875  ne^  tnat  tne 
shelter  deck  was  not  practically  a  complete  deck  for  all  purposes 
of  safety  to  the  ship  and  cargo.  Thereafter  shelter-deck  space 


186  MERCHANT  VESSELS 

was  exempt  from  measurement  under  British  rules.  The  present 
condition  in  the  United  States  is  well  illustrated  by  a  quotation 
from  the  Customs  Regulations: 

By  closed-in  spaces  is  to  be  understood  spaces  which  are  sheltered 
from  the  action  of  the  sea  and  weather,  even  though  openings  be  left 
in  the  inclosure.  Measuring  officers  will  exercise  due  vigilance  that 
the  intent  of  the  law  in  this  respect  is  not  evaded.  It  should  be  borne 
in  mind,  however,  that  no  closed-in  spaces  above  the  upper  deck  to  the 
hull  are  to  be  admeasured  unless  available  for  cargo  or  stores  or  the 
berthing  or  accommodation  of  passengers  or  crew.  .  .  .  Whether  for 
the  purpose  of  measurement  a  deck  is  to  be  regarded  as  an  upper  deck 
or  as  the  shelter  deck  is  to  be  determined  in  each  instance  both 
by  the  character  and  structural  conditions  of  the  erection,  and  by  the 
purpose  to  which  the  between-deck  is  devoted. 

What  the  real  "  intent  of  the  law  "  is  has  yet  to  be  discovered, 
but  the  practical  result  is  that  not  all  space  is  measured  and  yet 
until  recently  vessels  were  not  as  leniently  treated  as  under 
British  measurement. 

8.  Method  of  Measurement  of  Between-Deck  Spaces. —  The 
space  above  the  tonnage  deck  and  under  the  upper  decks  of  the 
vessel  is  measured  by  an  abbreviation  of  the  system  applied  to 
the  section  below  the  tonnage  deck  —  in  brief,  the  use  of  only 
one  breadth  at  each  division  point  on  the  tonnage-length  instead  of 
five  or  seven.     The  length  between  decks  is  taken  at  the  middle 
of  the  height  of  the  'tween-deck  space,  from  inside  of  stem  to 
inside  of  stern  (line  AB,  Diagram  63).     This  length  is  divided 
into  the  same  number  of  equal  parts  as  the  tonnage  deck  and 
at  each  of  the  points  of  division  one  breadth  is  measured   (in- 
dicated by  CD,  EF,  GH,  IJ,  J(L,  etc.,  on  Diagram  63).     The  ap- 
plication of  Simpson's  rule  to  these  breadths  will  give  the  area 
of  an  imaginary  deck  midway  between  the  tonnage  deck  and 
the  upper  deck.     This  multiplied  by  the  average  height  between 
the  two  decks  will  give  the  cubic  contents  in  feet  and  the  ton- 
nage is  ascertained  by  dividing  this  result  by  100.     If  there  are 
more  than  three  decks  the  tonnage  between  other  decks  is  ascer- 
tained in  the  same  manner. 

9.  Superstructures  and  Closed-in  Spaces. —  In  addition  to  the 
space  between  decks  the  vessel  may  contain  a  forecastle,  bridge, 
poop,  side  houses,  deck  houses,  spaces  for  steering  gear,  etc.,  above 
decks.     The  method  for  measuring  the  contents  of  such  spaces 


GROSS  TONNAGE  187 

is  an  abbreviation  of  that  used  for  'tween-deck  spaces.  At  the 
middle  of  the  height  the  mean  length  is  ascertained  and  divided 
into  an  even  number  of  equal  parts  approximately  the  size  of  the 
divisions  of  the  tonnage  length  and  at  each  of  such  points  of 
division,  at  the  middle  height,  breadths  are  measured.  To  the 
sum  of  the  end  breadths  add  four  times  the  sum  of  the  even- 


FIG.   63. —  MEASUREMENT  OF   'TWEEN-DECK   SPACES 

numbered  breadths  and  twice  the  sum  of  the  odd-numbered 
breadths  and  multiply  the  whole  sum  by  one-third  of  the  common 
interval  between  the  breadths.  The  result  is  the  approximate 
area  of  an  imaginary  horizontal  plane  midway  between  the 
deck  and  the  roof  of  the  superstructure  which,  multiplied  by 
the  mean  height  of  said  superstructure,  gives  the  area  of  the 
same  in  cubic  feet.  No  space  is  measured,  however,  which  is 
open  to  the  weather  and  not  inclosed. 

We  have  indicated  the  method  of  measuring  spaces  below  the 
tonnage  deck,  spaces  between  the  tonnage  and  upper  decks  and 
superstructures  above  decks,  and  it  now  remains  to  indicate  those 
spaces  which  are  exempted  from  measurement,  whether  below  or 
above  the  tonnage  deck. 

10.  Spaces  Exempt  below  the  Tonnage  Deck. —  These  are 
principally  spaces  between  ribs  and  floor  beams  since  their  use  for 
cargo  is  restricted  and  water-ballast  spaces  available  for  no  other 
purpose. 


i88  MERCHANT  VESSELS 

ii.  Spaces  Exempt  above  the  Tonnage  Deck. —  These  are 
excluded  from  gross  tonnage,  either  because  they  are  not  enclosed, 
or  by  reason  of  their  use  for  a  purpose  which  makes  them  un- 
available for  cargo  or  passengers.  They  contribute  nothing  to 
the  earning  capacity  of  the  vessel. 

a.  Spaces  Exempt  because  Unenclosed. —  It  is  the  almost  uni- 
versal rule  to  exempt  the  space  occupied  by  hatchways  up  to  ^2. 
of  i  per  cent  of  the  gross  tonnage  and  to  measure  all  space  used 
for  this  purpose  in  excess  of  this  amount.     Permanent  erections 
with  openings  in  the  sides  or  ends,  unavailable  for  cargo  or  pas- 
senger use,  are  exempt. 

b.  Spaces  Exempt  because  of  Their  Purpose. —  In  addition  to 
unenclosed  spaces  it  has  been  customary  for  many  years  in  all 
countries  to  exempt  from  measurement  certain  spaces  which  were 
not  available  for  the  carriage  of  cargo  or  passengers  or  were  mere 
conveniences  for  the  latter. 

1 i )  Water-Ballast  Space. —  Water-ballast  space  above  the  ton- 
nage deck  is  comparatively  unusual.     Any  such  space  is  included 
in  gross  tonnage.     A  notable  case  of  water-ballast  above  the  ton- 
nage-deck is  the  self-trimming  vessel  described  in  Chapter  V. 

(2)  Machinery    Spaces. —  The   space   occupied   by   a    donkey 
engine  and  boiler  is  measured  if  below  decks  but  exempt  if  above 
decks  and  not  connected  with  the  engine  room.     If  so  connected 
it  is  measured  although  deducted  later  in  arriving  at  net  ton- 
nage (see  next  chapter).     Above  the  crown  or  top  of  the  actual 
engine-room  a  closed-in  space  is  frequently  provided  for  light 
and  air  purposes.     This  space  is  not  added  to  the  gross  tonnage 
ordinarily  but  may  be  if  the  owner  so  requests  and  it  is  reason- 
able in  extent,  above  the  upper  deck,  safe  and  seaworthy,  and 
cannot  be  used  for  any  purpose  other  than  machinery  or  the  ad- 
mission of  light  or  air  to  the  machinery  or  boilers.     The  incentive 
for   measuring  this   space   would   be   a    decreased   net   tonnage 
through  having  it  considered  as  engine-room  space  in  the  deduc- 
tion for  propelling  space  later.     The  defects  of  this  method  of 
treatment  are  obvious.     It  not  only  makes  the  rules  confusing  and 
subject  to  misinterpretation,  but,  in  addition,  allows  the  shipowner 
to  select  a  treatment  which  will  be  beneficial  to  him.  instead  of 
prescribing  a  rule  equitable  between  all  classes  of  vessels.     The 
mathematical  results  are  discussed  in  the  chapter  on  net  tonnage. 

(3)  Navigating    Spaces. —  The    spaces    for   the   anchor   gear, 


GROSS  TONNAGE  189 

steering  gear,  and  capstan  are  included  in  the  gross  tonnage  when 
situated  below  the  upper  deck  and  exempted  when  above  said  deck. 
In  the  former  case,  however,  they  are  subsequently  deducted, 
giving  the  same  net  result  as  if  they  had  never  been  measured. 
The  chart,  lookout,  and  signal  houses  are  measured  and  the  wheel 
house  is  exempted  by  the  United  States. 

(4)  Passenger  and  Crew  Accommodations. —  Cabins  and  state- 
rooms located  on  the  upper  deck  to  the  hull  are  included  in  the 
gross  tonnage,  but  temporary  arrangements  to  shelter  passengers 
on  short  voyages  are  exempted  with  the  consent  of  tonnage  offi- 
cials. This  brings  to  attention  a  rule  peculiar  to  the  United 
States,  providing  that  the  space  of  cabins  and  staterooms  for 
passengers  constructed  entirely  above  the  first  deck  which  is 
not  a  deck  to  the  hull  are  not  to  be  measured  pr  included  in  gross 
tonnage.  This  proyision  was  originally  intended  as  a  benefit  to 
coasting  and  river  steamers,  ocean  vessels  then  having  no  such 
construction,  but  when  the  latter  added  several  passenger  decks 
above  the  upper  deck  to  the  hull,  they  took  advantage  of  the  un- 
restricted wording  of  the  provision. 

Skylights  and  domes  are  exempt  while  galleys,  cookhouses,  con- 
denser and  bakery  spaces  are  exempt  if  situated  above  decks  and 
measured  if  below  decks,  but  in  the  latter  case  are  available  for 
deduction.  Companion  houses  are  exempt  except  when  used  for 
smoking  room  or  other  special  purposes.  Passageways  are 
measured  under  the  American  rules  when  serving  measured  spaces 
and  may  be  deducted  when  serving  deducted  spaces.  Toilet 
facilities  for  officers  and  crew,  under  American  rules,  are 
exempted  if  above  decks  and  measured 'and  deducted  if  below- 
decks.  Other  toilets  below  decks  are  measured  without  privilege 
of  deduction.  Above-decks  I  toilet  per  50  passengers,  not  ex- 
ceeding a  total  of  12,  is  exempt. 

12.  Principles   Governing  Gross  Tonnage  Measurement. — 

a.  What  It  Includes. —  Under  the  very  old  rules  gross  tonnage 
did  not  include  superstructures  but  there  were  practically  none  in 
existence.  After  the  change  in  vessel  construction  and  the  intro- 
duction of  the  Moorsom  system  the  gross  tonnage  included  the 
cubic  capacity  below  the  tonnage  deck,  between  the  tonnage  and 
upper  decks,  and  in  the  superstructures,  with  certain  exemptions 
which  varied  with  time  and  place  of  measurement. 


IQO  MERCHANT  VESSELS 

b.  Gross  Tonnage  Represents  Total  Cubic  Capacity. —  We  have 
seen  that  the  gross   tonnage   only   roughly  represents   the  total 
cubic  capacity  of  the  vessel,  though  such  is  theoretically  its  pur- 
pose.    Exemptions  based  on  logic,  precedent,  and  the  desire  to 
minimize  the  tonnage  upon  which  dues  were  payable  all  con- 
tributed to  defeat  the  theory,  and  even  the  Panama  rules,  the 
strictest  in  existence  and  with  the  avowed  object  of  measuring  all 
spaces,  in  fact  allow  some  exemptions. 

c.  Inclusions  and  Deductions. —  The  gross  tonnage  of  a  vessel 
is    determined    by    inclusions    and    exemptions.     It    might    be 
wondered  why  certain  items  are  included  in  the  gross  tonnage  only 
to  be  later  deducted  in  arriving  at  the  net  tonnage.     The  answer 
is  that  while  the  result  so  far  as  net  tonnage  is  concerned  is  the 
same,  to  reach  this  result  by  omitting  spaces  from  the  gross  ton- 
nage would  be  to  underestimate  the  latter.     Furthermore,  the  in- 
clusion of  as  much  space  as  possible  in  gross  tonnage  renders 
easier  the  calculation  of  net  tonnage  under  any  of  the  rules,  since 
spaces   not   measured    under   any   particular    set    of    rules    can 
be    readily    deducted,    but    spaces    omitted    from    consideration 
must  be  measured  and  accounted  for,  entailing  extra  labor  and 
time. 

d.  Principal  Factors  in  Gross  Tonnage. —  The  items  which  have 
been  differently  treated  by  various  rules  and  which  consequently 
principally  account  for  the  wide  discrepancies  in  results  attained 
are  the  interpretation  given  to  the  word  "  closed-ih  "  in  connec- 
tion with  decks  and  superstructures,  the  exemption  of  tiers  of 
cabins  and  staterooms  above  the  first  deck  which  is  not  a  deck 
to  the  hull,  the  varying  treatment  of  engine-room  light  and  air 
spaces,  spaces  contributory  to  the  feeding  and  comfort  of  the 
crew  and  passengers  and  passageways. 

e.  The  Relative  Strictness  of  Different  Rules. —  Naturally  all 
the  rules  do  not  give  the  same  gross  tonnage  for  the  same  vessel. 
In  1911  an  application  of  the  British,  Suez,  and  American  rules  to 
eight  vessels  showed  that  these  vessels  averaged  5216  tons  under 
the  British  rules,  5464  tons  under  the  Suez  rules,  and  5581  tons 
under  the  American  rules.     The  latter  exceeds  the  former  two 
results  largely  by  reason  of  the  interpretation  of  closed-in  spaces. 
The  measurements  under  the  Panama  rules  would  yield  a  greater 
result  than  any  of  the  above,  while  German  results  are  closely 
comparable  with  British. 


GROSS  TONNAGE  191 

f .  Exemptions  Prevalent  Causes  of  Difficulty. —  Illustrations  of 
this  fact  are  found  in  the  Bear  case  in  Great  Britain  where  the 
exemption  of  the  space  under  shelter  decks  has  caused  confusion 
between  British  and  other  rules  to  the  present  day,  and  has  had 
a  world-wide  influence  in  retarding  the  scientific  measurement  of 
vessels ;  in  the  British  Isabella  case  where  light  and  air  space  not 
included  in  gross  tonnage  was  held  to  be  deductible ;  in  the  Ameri- 
can requirement  that  higher  cabins  and  staterooms  be  exempted 
while  lower  ones  were  measured ;  in  the  efforts  of  the  Suez  Canal 
Company    to    obtain    an    equitable    international    basis    for    the 
measurement  of  vessels  of  different  nationalities  using  the  canal. 
In  formulating  the  rules  for  the  Panama  Canal  their  author  stated : 

The  logical  procedure  and  the  only  one  by  which  an  accurate  net 
tonnage  can  be  calculated  is  to  include  in  gross  tonnage  the  entire 
closed-in  capacity  of  a  vessel  and  to  deduct  therefrom,  in  calculating 
net  tonnage,  such  navigation  and  other  spaces  as  are  not  available 
for  the  accommodation  of  passengers  or  for  the  stowage  of  cargo. 

g.  Gross  Tonnage  and  Earning  Capacity. —  Two  vessels  might 
have  the  same  gross  tonnage  but  by  reason  of  low  engine  power 
considerably  more   space  might  be  available  in  one   for  cargo. 
In  a  passenger  steamer  and  a  freight   steamer  of   equal  gross 
tonnage  considerable  space  on  the  former  would  be  devoted  to 
comfort  and  speed  and  contribute  nothing  to  earning  power.     Pas- 
senger vessels  with  superstructures  for  passengers  would  be  en- 
titled to  considerable  exemption,   while   passenger   space   below 
decks  is  all  measured.     Gross  tonnage  would  measure  engine- 
room,  boiler,  and  fuel  space,  although  this  is  only  partly  con- 
tributory to  earning  power  and  its  proportion  to  gross  tonnage 
varies  greatly.     Therefore  net  tonnage  is   far  more   frequently 
used  as  a  basis  for  vessel  charges  and  tolls  than  gross  tonnage. 

h.  Defects  of  American  Rules. —  The  American  rules  yield  re- 
sults which  have  neither  the  merit  of  correctly  measuring  the  cubic 
capacity  nor  the  profit  of  sufficiently  understating  the  tonnage 
of  their  own  vessels.  The  British  and  German  rules  at  least  do 
the  latter.  On  the  one  hand,  passenger  accommodations  abc^ye 
the  first  deck  which  is  not  a  deck  to  the  hull  and  certain  navigation 
spaces  above  the  upper  deck  and  deck  loads  are  exempt,  while, 
on  the  other  hand,  "  closed-in  "  spaces  have  been  more  strictly 
construed  than  under  the  rules  of  foreign  nations. 


CHAPTER  XI 
NET  TONNAGE 

Gross  tonnage  approximately  measured  the  closed-in  capacity  of 
a  vessel ;  net  tonnage  measures  its  capacity  for  passengers  or 
cargo.  It  is,  therefore,  the  gross  tonnage  less  certain  deductions, 
principally  space  required  for  machinery,  fuel  and  the  crew.  The 
machinery  and  fuel  space  is  often  measured  by  a  somewhat 
arbitrary  method  so  that  the  deduction  is  in  excess  of  the  actual 
space  occupied,  but  this  will  be  seen  to  be  a  difficulty  inherent 
in  the  character  of  the  space  measured.  The  deductions  may 
be  divided  into  three  groups,  which  will  be  treated  in  the  order 
given:  deductions  for  propelling  machinery,  for  crew  space,  and 
for  navigation  spaces. 

Measurement  of  Propelling-Power  Space. —  The  measurement 
of  the  space  occupied  by  propelling  machinery  includes  (a)  ma- 
chinery and  boiler  space,  (b)  ventilating  space,  and  (c)  shaft 
tunnel.  By  reason  of  an  option  allowed  the  vessel-owner  under 
the  American  rules  it  is  always  necessary  to  measure  the  engine 
room,  whatever  its  size  may  be.  The  content  of  the  three  spaces 
referred  to  is  considered  to  be  the  product  of  the  mean  length, 
breadth,  and  depth 'of  such  spaces  divided  by  100.  From  the 
engine-room  space  proper  is  to  be  deducted  the  cubical  capacity 
of  any  cabins  or  storerooms  which  may  be  fitted  in  the  engine  room 
and  also  any  space  occupied  by  machinery  not  used  in  propelling 
the  ship. 

It  will  be  noticed  that  no  mention  has  been  made  of  the  very 
considerable  space  required  for  coal.  An  Atlantic  liner  may 
burn  from  500  to  700  tons  of  coal  per  day  and  her  bunkers  must 
be  capable  of  holding  from  4000  to  6000  tons,  a  cubic  capacity 
of  180,000  to  270,000  cubic  feet  or  2700  register  tons.  Two 
kinds  of  coal  bunkers  are  in  use:  side  bunkers  formed  by  parti- 
tioning off  the  space  beside  the  engine  and  boilers  amidships  and 
cross  bunkers,  formed  by  partitioning  off  a  portion  of  the  hold 
entirely  across  the  ship  approximately  amidships.  Both  the 

192 


NET  TONNAGE  193 

machinery  and  coal  bunkers  are  ordinarily  situated  amidships  be- 
cause in  this  position  the  consumption  of  coal  during  the  voyage 
does  not  cause  a  constantly  increasing  trim  by  the  head.  But 
in  oil  steamers,  where  oil  is  used  as  fuel,  the  machinery  may  be 
situated  in  the  stern  and  the  fuel  carried  both  fore  and  aft  in 
the  peak  and  double  bottom  tanks.  But  it  is  obvious  that  the 
amount  of  space  required  for  fuel  is  both  indeterminate  and 
changing.  It  will  depend  upon  the  duration  of  the  voyage  and 
the  possibility  of  frequently  and  economically  replenishing  the 
supply.  It  will  also  be  affected  by  the  efficiency  of  the  machinery, 
whose  inferiority  may  increase  the  coal  consumption  by  as  much 
as  20  per  cent,  and  by  the  quality  of  the  fuel.  The  vessel  engaged 
in  the  line  trade,  with  definitely  fixed  voyages,  may  be  able  to 
calculate  fairly  accurately  the  necessary  fuel,  while  the  tramp 
vessel  must  always  allow  a  considerable  margin  for  contingencies. 
These  considerations  led  to  fitting  vessels  with  movable  partitions, 
enabling  the  bunker  to  be  enlarged  or  contracted  as  necessity  re- 
quires and  the  same  space  to  be  used  indiscriminately  for  fuel 
bunkers  or  cargo.  It  is  therefore  impossible  definitely  to  designate 
the  fuel  space  and  accurately  measure  the  same,  and  it  can  only 
be  assumed  that  the  fuel  space  will,  on  the  average,  be  propor- 
tionate to  the  engine-room  space. 

Light  and  Air  Spaces. —  Because  of  the  peculiar  consideration 
given  to  light  and  air  spaces  it  is  necessary  to  consider  these 
separately.  It  will  be  recalled  that  the  space  above  the  crown 
or  top  of  the  actual  engine-room  space,  provided  for  purposes 
of  light  and  air,  is  not  ordinarily  included  in  the  gross  tonnage, 
but  may  be  if  the  owner  so  requests.  If  included  in  the  gross 
tonnage  it  may  also  be  added  to  the  engine-room  space  so  as  to 
increase  this  space  and  consequently  the  deduction  allowed  for  it. 

Deductions  for  Propelling  Space. —  The  American  rules  com- 
bine two  forms  of  allowance  for  propelling-power  space.  Let 
us  consider  screw-propelled  vessels  exclusively.  If  the  measure- 
ment shows  the  actual  space  occupied  by  the  engine  room  in- 
cluding the  shaft  tunnel  to  be  13  per  cent  or  less  of  the  total 
gross  tonnage  of  the  vessel,  1^4  times  the  tonnage  of  the  space 
actually  so  occupied  shall  be  deducted  from  the  gross  tonnage  in 
order  to  arrive  at  net  tonnage.  This  is  the  so-called  Danube 
principle,  the  allowance  for  fuel  space  being  a  percentage  of  the 
engine-room  space.  If,  however,  the  space  actually  occupied  by 


194  MERCHANT  VESSELS 

the  engine  room,  including  the  shaft  tunnel,  proves  to  be  over 
13  per  cent  but  less  than  20  per  cent  of  the  total  gross  tonnage 
there  shall  be  deducted  32  per  cent  of  the  gross  tonnage  of  the 
vessel.  This  is  the  so-called  percentage  principle,  the  allowance 
for  fuel  space  being  a  percentage  of  the  gross  tonnage  of  the 
vessel.  If,  in  the  third  place,  the  engine-room  space  totals  20  per 
cent  or  over  of  the  gross  tonnage  of  the  vessel  the  allowance  shall 
be  either  32  per  cent  of  the  total  gross  tonnage  or  i%  times  the 
actual  space,  as  the  owner  may  prefer.  This  gives  a  choice,  when 
the  tonnage  of  the  actual  space  exceeds  19.99  Per  cent  °f  tne 
gross  tonnage,  of  the  percentage  or  Danube  principle.  The  fol- 
lowing extract  from  Walton's  Know  Your  Own  Ship  will  show 
the  significance  of  these  provisions : 

So  far  as  ordinary  screw  steamers  are  concerned,  the  modern  ship- 
building practice  is  to  arrange  that  the  tonnage  of  the  machinery 
spaces,  either  independently  or  together  with  a  part  or  the  whole  of 
the  light  and  air  spaces  above  the  upper  deck,  amounts  to  at  least 
13  per  cent  of  the  gross  tonnage.  To  design  the  machinery  spaces  of 
such  vessels  so  that  their  aggregate  tonnage  amounts  to  less  than 
13  per  cent  of  the  gross  tonnage  causes  the  propelling  space  deduc- 
tion to  be  estimated  at  1^4  of  the  total  actual  machinery  space,  as 
previously  stated.  This  produces  a  comparatively  small  propelling 
space  deduction.  For  instance,  suppose  we  have  a  screw  steamer  of 
100  tons  gross  tonnage.  If  the  actual  propelling  space  amounts  to 
just  over  13  tons  of  measurement,  then  the  deduction  is  32  tons;  but 
if  the  propelling  space  measurement  reaches  only  i2l/2  tons,  then  the 
deduction  is  only  1^4  of  12X2,  or  21.87  tons.  On  the  other  hand, 
nothing  is  to  be  gained  by  enlarging  the  engine  and  boiler  spaces  so 
long  as  they  do  not  exceed  20  per  cent  of  the  gross  tonnage.  When, 
however,  20  per  cent  is  reached  or  exceeded,  it  has  been  shown  (see 
below)  how  preferable  is  the  deduction  of  i%  times  the 
actual  machinery  space  measurement  to  that  of  32  per  cent  of 
gross  tonnage. 

Suppose  the  gross  tonnage  of  a  screw  steamer  be,  say,  100,  and  the 
actual  propelling  space  20.  The  deduction  of  1^/4  times  the  actual 
propelling  space  would  be  1^4  of  20,  or  35,  which  is  greater  than  32 
as  a  deduction.  ...  It  can  now  easily  be  understood  how,  in  vessels 
with  large  propelling  space,  the  register  tonnage  is  sometimes  rela- 
tively small,  especially  when  the  crew  spaces  and  other  deductions  are 
also  large. 

The  following  table  gives  a  summary  of  the  treatment  of  pro- 
pelling-power spaces  for  both  screw  and  paddle-wheel  steamers 
under  the  American  rules. 


NET  TONNAC7E 


195 


Type  of  steamer 

Percentage  of  pro- 
pelling-power space 
to  gross  tonnage 

Deduction 

Paddle-wheel 

20  per  cent  or  under 
Over  20  and  under 
30  per  cent 
30  per  cent  pr  over 

150  per  cent  of  actual  space 
37  per  cent  of  gross  tonnage 
37  per  cent  of  gross  tonnage 
or 
150  per  cent  of  actual  space 

Screw 

13  per  cent  or  under^ 
Over  13   and  under 
20  per  cent 
20  per  cent  or  over 

175  .per  cent  of  actual  space 
32  per  cent  of  gross  tonnage 
32  per  cent  of  gross  tonnage 
or 
175  per  cent  of  actual  space 

This  is   further  illustrated  by  the  accompanying  diagram  in 
which  the  rising  line  indicates  the  increasing  deduction  for  a  rising 


FIG.  64 


196  MERCHANT  VESSELS 

ratio  of  propelling-power  space  to  total  gross  tonnage  in  a  10,000- 
ton  steamer. 

It  will  be  noted  from  this  diagram  that  a  ratio  of  propelling 
space  to  gross  tonnage  anywhere  below  13.1  per  cent  entails  a 
deduction  proportionate  to  the  propelling  space,  but  that  at  13.1 
per  cent  the  deduction  abruptly  jumps  from  22.75  Per  cent  °f 
gross  tonnage  to  32  per  cent  of  the  same.  Where  the  propelling 
space  would  naturally -approach  13  per  cent,  therefore,  the  tendency 
is  to  make  it  13.1  per  cent  in  order  to  obtain  the  larger  deduc- 
tion. But  there  is  no  incentive  to  make  it  greater  than  13.1  per 
cent,  for,  even  though  it  be  increased  to  19  per  cent,  the  deduc- 
tion is  exactly  the  same.  When  the  ratio  of  propelling  space 
to  gross  tonnage  becomes  20  per  cent,  however,  assuming  the 
owner  take  advantage  of  his  option,  the  deduction  may  be  abruptly 
increased  to  35  per  cent,  and  thereafter  the  deduction  is  propor- 
tionate again  to  the  amount  of  propelling-power  space.  There 
are  thus  three  sections  of  the  curve  on  the  diagram,  two  of  which 
are  proportionate  to  propelling-power  space  and  one  proportionate 
to  the  gross  tonnage  of  the  vessel.  It  is  difficult  to  see  how 
these  can  be  logically  or  economically  justified.  In  the  succeed- 
ing chapter  we  shall  see  how  propelling-power  space*  is  treated 
under  the  laws  of  other  nations  and  particularly  the  Panama 
rules. 

Deductions  for  Crew  Space. — The  term  "crew"  includes  the 
entire  personnel  on  the  articles  and  crew  list  —  sailors,  firemen, 
mechanics,  petty  officers,  officers,  doctors,  stewards,  etc.,  and  the 
spaces  involved  are  the  sleeping  quarters,  lavatories,  bathrooms, 
toilets,  wardrooms,  galleys,  shelter  for  condensing  water,  chief 
engineer's  office,  wireless  office,  mess  rooms  and  passages  ex- 
clusively serving  these  spaces.  All  of  the  space  so  occupied  is 
to  be  deducted  from  gross  tonnage,  unless  used  by  or  for  pas- 
sengers. But  depending  upon  the  date  of  construction  of  the 
vessel,  the  law  requires  a  space  of  from  72  to  100  cubic  feet 
and  from  12  to  16  superficial  feet  to  be  allotted  to  each  seaman 
or  apprentice,  and  requires  also  that  suitable,  clean,  and  sanitary 
spaces  be  allotted  for  other  requirements  of  the  crew.  No  deduc- 
tions from  tonnage  will  be  made  unless  there  is  permanently 
cut  in  a  beam  and  over  the  doorway  of  every  such  place  the 
number  of  men  it  is  allowed  to  accommodate.  It  will  be  recol- 


NET  TONNAGE 


197 


BRITISH  STEAMSHIP  Stephen 
(Particulars  given  on  p.  211) 


TONNAGE 

as  given  by  following  certificates: 


United  States 


British 


Suez 


•?6o7  76 

7607  76 

7607  76 

Forecastle           

O^™/  •O" 

84  02 

ovjv'/  "jr* 
8d.Q2 

JW/.^U 

Bridge  space  

Wi  KX 

•JQI   IO 

•7^7  07 

17778 

o^o*1" 
17778 

Jr\/J^ft 

Side  houses  

762 

x//v'-' 

762 

2  ^2 

10678 

106  78 

**^- 
j  jr  2O 

Light  and  air  

.iv/vj./u 

57.28 

Ayw./u 
5728 

Upper  'tween-decks  added. 

06804 

12-6  J.  I 

Light  and  air  added  .  . 

j;4,QQ 

Excess  hatchxvavs  added  .  . 

II  rr 

71  87 

Galleys,  cook-houses,  water 
closet,       bath,       chart 
house,  wheel  house,  etc 

o  A.«J/ 
1  17  21 

Gross  tonnage   

547O.72 

AA"\A  8/1 

cj.77  70 

DEDUCTIONS 

Propelling    power,    32    per 
cent       

I7sO  5%O 

IJ.IQ  1  1 

J^T//'/" 

Actual  plus  75  per  cent  .  . 

*/y*y 

itLy-lj 

IIO2  77 

Crew  space 

141  27 

141  27 

Doctor    engineers    etc 

16.46 

Officers 

3681 

Master 

Q  22 

O.22 

Boatswain's  stores 

17.71 

17.71 

Chart  hou^e                         .  . 

4.77 

4.77 

4-7"? 

Water  ballast  spaces 

7J.  OI 

^  1    QT 

Gallevs  cook-houses  water- 

O-r-VA 

a^r-y* 

16.11 

\Vheel  house 

6.7O 

^teering  gear 

28.28 

\\  ireless  apparatus 

7.37 

Total  deductions             .  • 

IQ;8.74 

l626.OQ 

1274.10 

Net  tonnage           .  .    .  . 

75II.Q8 

2807.85 

4203.30 

lected  that  many  such  spaces  are  exempt  if  above  decks  and  we 
now  find  that  when  below  decks,  although  measured,  they  are 
deducted.  Likewise,  any  properly  constructed  and  reasonable 
space  for  the  use  of  the  master  of  the  vessel  is  deducted.  These 


198  MERCHANT  VESSELS 

spaces  are  measured  by  taking  the  product  of  the  three  dimensions 
when  bounded  by  practically  flat  surfaces  and  in  other  cases  by 
the  Moorsom  system. 

Deductions  for  Navigation  Space. —  These  include  any  spaces 
devoted  exclusively  to  the  working  of  the  helm,  the  capstan,  and 
the  anchor  gear ;  or  spaces  used  for  keeping  the  charts,  signals, 
and  other  instruments  of  navigation,  and  boatswain's  stores ;  and 
the  space  occupied  by  the  donkey  engine  and  boiler,  if  connected 
with  the  main  pumps  of  the  ship.  In  the  case  of  a  vessel  propelled 
wholly  by  sails  there  may  be  deducted  a  space  for  the  storage  of 
sails,  not  exceeding  2^/2  per  cent  of  the  gross  tonnage.  All  such 
space  must  be  permanently  marked  "  Certified  for  .  .  .  (boat- 
swain's stores,  chart  house,  etc.).  .  .  ." 

The  preceding  table  shows  the  calculation  of  tonnage  items 
for  a  common  type  of  vessel  on  three  tonnage  certificates. 

PRINCIPLES  OF  NET  TONNAGE 

Reviewing  the  facts  presented  in  this  chapter  the  following 
principal  features  of  net  tonnage  are  noted : 

1.  Net  tonnage  consists  of  gross  tonnage  less  deductions  for 
propelling  space,  crew  space,  and  navigation  spaces.     There  is  no 
unanimity  among  nations  as  to  the  method  of  arriving  at  the  total 
deductions. 

2.  Net  tonnage  represents  theoretically  the  earning  capacity  of 
the  vessel,  the  theoretical  purpose  being  defeated  by  arbitrary  rules 
for  engine-room  deductions  and  the  desire  to  favor  native  vessels. 

3.  Net  tonnage  is  affected  by  the  inclusion  and  exclusion  of 
items  from  the  gross  tonnage  and  by  deductions  from  gross  ton- 
nage.    Thus,  the  exemption  of  shelter-deck  space  from  measure- 
ment  affects   both   gross   and   net  tonnage,   while  the  character 
of  the  machinery-space  deduction  affects  only  the  net  tonnage. 
It  is  apparent  that  the  correct  net  tonnage  can  be  arrived  at  only 
by   accurately  ascertaining  the   gross  tonnage  and   making   fair 
deductions  for  machinery,  crew,  and  navigation  spaces. 

4.  The  most  important  provision  of  a  code  of  tonnage  rules 
is   that   determining1   the    deduction   for   propelling-power   space, 
for  this  forms  from  %  to  %  of  the  total  deduction  made.     The 
deductions  for  crew  and  navigation  spaces  comprise  from  15  to 
25  per  cent  of  the  total  deduction. 


[         DEPARTMENT  OF  COMMERCE 

BUREAU  OF  NAVIGATION 
PAET  I.—"  Measurement  of  Vessels,"  1919 


TONNAGI 


Register  Length ..s3...??_..G_^_A 

Register  Breadth .d~..Jf=.._.'. 

Register  Depth  (Midship  Section) ^..7^.. 

Height  under  Spar  Dcc\.... 

SECTION  I.  SECTIO 

--I 

TONNAGE  DEPTHS- 

Common    Inlerral   between    Breadths  to  ; 
nearest  hundredth*  of  a  foot 

NJrenadCths.f  Multipliers.         Breadths.         Products.         Breadths. 

1 

2  4 

3  2 

4  - I.J...3..J-/ 

ffff/  .^ sfff/J/tff'ttt    , ._,  'ffrttfrumftrtert/tiffa't/ri /-^// 

rv/i'fetisri' ft*tf'r-r/uM/±  /-//X///.»  __ 

frnsf/A//.\  6*r/>  //ajy  nyafrrn/ t/f  Mu  /art 

:n  v/tt/rr  mv  Aa/it/ a/iU  seat,  at  t/tt  /br/t/f       ^\  _ 

.  iff  t/ifjrat  ///or  //*//y////// \\'//tr /////rrfrr'/ tt/rs/ ^ 


FlG.   66. —  TONNAGE  CERTIFICATE 


,seb 
JUT  ^ngine-  uotf    ^  V       .     i  and  the  a 

3.  Net  tonnage  is  affected  by  the  inciu 
items  from  the  gross  tonnage  and  by  deductioi 
nage.     Thus,  the  exemption  of  shelter-deck  spacv 
ment   affects   both   gross   and   net  tonnage,   whiK 
of  the  machinery-space  deduction  affects  only  tht 
It  is  apparent  that  the  correct  net  tonnage  can  be  ai 
by   accurately  ascertaining  the   gross  tonnage  and 
deductions  for  machinery,  crew,  and  navigation  spac- 

4.  The  most  important  provision  of  a  code  of  ton 

is   that   determining  the    deduction   for   propelling-powe 
for  this  forms  from  %  to  %  of  the  total  deduction  made.     The 
deductions  for  crew  and  navigation  spaces  comprise  from  15  to 
25  per  cent  of  the  total  deduction. 


isftf present  /ftaxfrt  <//////>  //  //t/tzf/t  vft/ic  M/'tt'-fS .  fortes,  aft<M/ui/ 


Me .\trtrt  vrs.\f/n>as6t»/ft/t  tAf.  rent  / 


Aan/ty  trrti/} fit  that /Aes*ut  y<Ksr/is 
mast-  .a 


.^  tfvt.  Arrnyu/fr6tmtff/e 


/fff.  MatsAr /neasu/rs at 


Aai/my  t/y/mt  fa  /Arrfwi ////>/•///  <///// 


fa/tar  «/ttf  sea/,  att/tt  fart 


^SEX:': 


BWH«' 

FlG.   66. —  TONNAGE  CERTIFICATE 


200  MERCHANT  VESSELS 

5.  The  Suez  and  Panama  rules  give  the  greatest  net  tonnage, 
being  followed  by  the  American,  German,  and  British. 

6.  While  there  is  confusion  in  the  exemption  and  deduction  of 
navigation  spaces  and  the  treatment  of  light  and  air  spaces,  it 
will  later  be  seen  that  the  deductions  for  propelling-power  space 
are  the  principal  cause  of  understatement  of  net  tonnage  and  the 
variable  net  tonnage  results  under  the  different  rules. 

7.  Net  tonnage,  which  excludes  a  large  number  of  spaces  un- 
usable for  passengers  or  cargo,  is  evidently  .a  much  fairer  basis 
for  the  assessment  of  vessel  charges  than  gross  tonnage,  which 
would  favor  the  slow  vessels  and  cargo  carriers  at  the  expense 
of  the  high-powered  and  passenger  vessels. 

8.  The  American  rules   for  ascertaining  net  tonnage  are  de- 
fective in  that  thev  use  the  unsatisfactory  combination  of  per- 
centage and  Danube  rules  for  ascertaining  machinery-space  de- 
ductions, allow  light  and  air  space  to  be  either  exempted  or  de- 
ducted, and  do  not  treat  crew  and  navigation  spaces  consistently. 

EXAMPLE  OF  MEASUREMENT  CALCULATIONS 

Figures  65  and  66  are  examples  of  an  American  tonnage  certifi- 
cate and  a  form  for  the  calculation  and  recording  of  particulars  of 
tonnage.  On  the  face  of  the  latter  form  will  be  noticed  the  par- 
ticulars of  the  vessel,  the  measurements  necessary  for  the  cal- 
culation of  tonnage,  the  tonnage  under  the  tonnage  deck,  the 
inclosed  spaces  above  the  tonnage  deck  and  spaces  to  be  deducted, 
a  summary  of  the  tonnage  and  the  surveyor's  certificate.  The  re- 
verse side  is  a  continuation  of  the  exempted  and  deducted  spaces. 

REFERENCES 


1.  JOHNSON,   E.   R. :     "  Report   to   Secretary  of   War   on   Panama 

Canal  Traffic  and  Tolls."  Washington,  1913.  Chaps.  Ill,  IV, 
V,  VI.  VII,  VIII,  IX,  X,  XI,  XII,  XIII  and  XIV,  Part  III 
and  Appendices  1-16,  and  18.  (A  comprehensive  discussion 
of  the  whole  subject  of  tonnage  measurement  and  its  relation 
to  canal  tolls.  Bibliography  on  tonnage  measurement.) 

2.  Great    Britain,    "  Report    of    Royal    Commission    on    Tonnage," 

Parliamentary  Papers.  London,  1881,  ^3074.  In  Reports 
from  Commissioners,  Vol.  49.  (Reprinted  in  Reference  I.) 


NET  TONNAGE  201 

3.  Great   Britain,  "  Report  of  Board  of  Trade  Committee,   1906." 

London,  1906,  Cd-3O45.  (A  discussion  of  deductions  for  pro- 
pelling power.) 

4.  HERNER,      HEINRICH  :    Hafenabgaben     und     Schiffvermessung. 

G.  Fischer,  Jena,  1912.  (A  discussion  of  the  history  of  ton- 
nage measurement  in  Germany  and  other  countries,  the  Ger- 
man and  Suez  rules  and  vessel  and  port  charges  based  on 
tonnage.) 

5.  MOORSOM,  G. :      Laws  of  Tonnage.     London,   1852.     (A  discus- 

sion of  the  principles  upon  which  tonnage  should  be  based, 
defects  of  then  existing  rules  and  a  description  of  the  methods 
later  known  as  the  Moorsom  system.) 

6.  MOORSOM,  G. :     "  On  the  New  Tonnage  Taw."     Transactions  of 

the  Institution  of  Naval  Architects,  Vol.  I,  pp.  128-144.  Lon- 
don, 1860. 

7.  Nautical  Magazine.     London,  1889-1890,  Vols.  Iviii  and  lix,  pp. 

1-15.  89-101,  173-186,  261-269,  356-367,  722-735,  804-824, 
985-998,  i-n,  89-96.  (A  complete  history  of  the  development 
of  tonnage  measurement  in  Great  Britain,  and  an  explanation 
of  the  Moorsom  system.) 

8.  WHITE,  W.  H. :     Manual  of  Naval  Architecture.     Murray,  Lon- 

don, 1894.  Chap.  II.  (Brief  history  of  the  development  of 
tonnage  measurement,  early  British  laws  and  present  British 
measurement,  criticism  of  engine-room  deductions,  comparison 
of  British  and  Suez  rules,  international  tonnage,  and  alterna- 
tive systems  of  measurement.) 

9.  "  Report  of  the  International  Tonnage   Commission,   Constanti- 

nople, 1873."     (Reprinted  in  Reference  i.) 

10.  BERET,  V.:    "Etude  snr  le  Jaugeagc"  report  to  the  President. 

Societe  anonyme  de  publications  periodiques,  P.  Mouillot,  Paris, 
1905.  (History  of  tonnage,  the  Moorsom  system,  international 
tonnage,  relation  between  tonnage  and  carrying  capacity,  prin- 
ciples and  methods  of  Suez  tonnage,  comparative  tables  of 
British,  German,  and  French  measurement.)  (Comparative 
tables  and  History  of  Suez  measurement  translated  in  Refer- 
ence i.) 

11.  Germany,  Imperial  Department  of  Interior:     "The  Measurement 

of  Seagoing  Vessels."  Berlin,  1908.  (German  rules.  Trans- 
lated in  Reference  i.) 

12.  Germany,   Imperial   Department   of  Interior:     "Instructions   for 

Ship  Measurement."     1895.     (Translated  in  Reference  i.) 

13.  HOLMES,  G.  C.  V.:    Ancient  and  Modern  Ships.     Wyman  &  Sons, 

London,  1906.  Vol.  II,  Appendix  II.  (Brief  history  of  ton- 
nage.) 

14.  Great  Britain,  Board  of  Trade:     "Instructions  and  Regulations 

for  Measurement  of  Ships  and  Tonnage."  London,  1913. 
(British  and  Suez  measurement,  British  tonnage  laws.) 


202  MERCHANT  VESSELS 

15.  JOHNSON   AND  HUEBNER:    Principles  of  Ocean   Transportation. 

D.  Appleton  &  Co.,  New  York,  1918.     Chap.  IV.     (Brief  ele- 
mentary discussion  of  tonnage  measurement.) 

16.  WALTON,  THOMAS:    Know  Your  Own  Ship.     Griffin  &  Co.,  Lon- 

don, 19 r?.     Chap.  VIII.     (Good  summary  of  the  present  Brit- 
ish, Suez,  and  Panama  measurement  systems.) 

17.  Suez   Maritime   Canal   Co. :     "  Memorandum   on   Application   of 

Rules  of  1904."     Paris,  1909.     (Contained  in  Reference  i.) 

18.  United  States,  Navigation  Laws,  Sections  13-27.     (Contained  in 

Reference  i.) 

19.  United   States,    Customs   and   Regulations,   Arts.   71-87.     (Con- 

tained in  Reference  i.) 

20.  United  States,  Department  of  Commerce,  Bureau  of  Navigation: 

"  Regulations  for  Measurement  of  Vessels,  Measurement  Laws 
and  Suez  Canal  Regulations."    Washington,  1919. 
21. -United  States,  Commissioner  of  Navigation:    Annual  Reports  of 
1914,  1915,  1916,  1917,  1919. 


CHAPTER  XII 
COMPARISON  OF  MEASUREMENT  RULES 

The  tonnage  laws  of  various  nations  have  differed  from  the 
earliest  times.  We  have  previously  described  some  of  the  older 
rules  for  calculating  tonnage,  noting  that  they  were  dissimilar 
in  various  countries  at  the  same  time,  undergoing  changes  with 
time  in  all  countries  and  in  the  early  periods  even  different  in  the 
same  country  at  the  same  time,  as  evidenced  by  the  local  rule 
in  Philadelphia  about  1850.  Constant  but  slow  progress  has  been 
made  toward  uniformity  with  the  result  that,  while  various  nations 
and  the  Suez  Canal  Company  make  their  own  measurement  rules, 
these  have  constantly  tended  to  become  more  harmonious. 

PRESENT-DAY  RULES 

i.  Great  Britain. —  Early  British  rules  were  mere  approxima- 
tions of  the  capacity  of  vessels,  the  estimates  of  two  individuals 
as  regards  the  same  vessel  in  1650  often  differing  by  30  per  cent. 
The  first  measurement  law  was  passed  in  1694  and  repealed  in 
1696  and  another  act  of  limited  application  was  passed  in  1719, 
but  the  first  really  important  law  was  that  requiring  the  use  of 
"  Builders'  Old  Measurement "  rules  in  1773.  This  act,  which 
was  in  effect  until  1835,  was  intended  to  express  the  tonnage 
of  vessels  in  terms  of  dead  weight.  It  was  easily  evaded  and 
produced  unseaworthy  vessels,  so  that  in  1835  the  *'  New  Measure- 
ment "  law  was  passed,  changing  the  rules  from  a  dead-weight 
to  an  internal  capacity  basis  and  providing  for  a  limited  number  of 
measurements  in  specified  positions.  This  law,  though  subject 
to  evasion,  continued  until  the  adoption  of  the  Moorsom  system 
in  1854,  a  system  which  forms  the  foundation  for  modern 
measurement  rules,  that  of  the  United  States  included.  The  Act 
of  1854  had  allowed  an  exemption  from  tonnage  for  crew  houses 
on  deck  as  an  incentive  to  more  suitable  crew  quarters.  Small 
vessels  in  which  this  was  impossible  were  placed  at  a  disadvantage 

203 


204  MERCHANT  VESSELS 

and  an  act  of  1867  provided  that  under  certain  conditions  a  de- 
duction from  tonnage  should  be  allowed  to  the  extent  of  the 
actual  cubic  content  of  all  places  occupied  by  the  crew  with  the 
exception  of  the  master.  An  amendment  in  1889  provided  that 
no  deduction  should  be  made  from  gross  tonnage  for  any  space 
which  had  not  previously  been  measured,  permitted  the  exemption 
of  reasonable  light  and  air  spaces,  and  specified  deductions  for 
certain  navigation  spaces.  Every  seagoing  vessel  of  over  15  tons 
burden  must  be  registered  and  to  obtain  a  certificate  of  registry 
must  be  surveyed  and  measured  by  a  surveyor  appointed  by  the 
Board  of  Trade,  which  is  a  government  agency.  This  is  done 
under  rules  and  instructions  issued  by  the  Board  of  Trade,  in 
accordance  with  the  laws  requiring  the  same.  Irrespective  of  the 
British  requirement,  without  this  document  the  vessel  would  be 
detained  for  measurement  at  every  port  of  call. 

It  is  important  to  note  that  in  1862  a  law  was  enacted  in  Great 
Britain  providing  that  when  any  foreign  nation  adopted  the 
British  system  of  measurement  under  the  Act  of  1854  the  ton- 
nage of  vessels  as  stated  in  their  national  certificates  would  be  ac- 
cepted at  British  ports  without  remeasurement.  A  special  clause 
has  been  inserted  in  every  tonnage  act  since  this  date,  making 
it  a  part  of  the  Act  of  1854.  This  opened  the  way  to  international 
recognition  of  national  tonnage  certificates. 

2.  Germany. —  In  Germany  a  number  of   different  rules   for 
tonnage  had  been  in  use  in  the  several  German  states,  but  in 
1873  the  Moorsom  system  became  the  official  measurement  method. 
The  German  tonnage  differed  from  British,  however,  in  respect 
to  the  deduction  for  propelling-power  space  and  the  treatment  of 
shelter-deck  space.     In   1888  the  German  law  was  amended  by 
increasing  the  number  of  transverse  areas  measured  in  large  ships, 
fixing  a  sliding  scale  of  allowances  for  crew  and  navigation  spaces 
and   for  the  exemption  of  hatchway  space.     In    1895   the   per- 
centage rule  for  propelling-power  deductions  was  adopted.     The 
measuring  is  conducted  by  measurement  boards  appointed  by  the 
State  governments,  supervised  by  the  Bureau  of  Registry,  which 
until  the  overthrow  of  the  Imperial  government  was  under  the 
direction  of  the  Imperial  Chancellor. 

3.  United  States. —  A  system  somewhat  similar  to  the  "  Build- 
ers' Old  Measurement "  rules  of  Great  Britain  was  in  force  in 
the  United  States  until  the  adoption  of  the  Moorsom  system  in 


COMPARISON  OF  MEASUREMENT  RULES  205 

1865.  I*1  a  single-deck  vessel  by  the  Act  of  1789  the  tonnage 
was  the  product  of  ( i )  the  length  measured  from  the  fore  part  of 
stem  to  the  after  part  of  sternpost  less  three-fifths  of  the  breadth, 

(2)  the  breadth  at  the  broadest  part  above  the  main  wales,  and 

(3)  the  depth  from  the  under  side  of  the  deck  to  the  ceiling  in 
the  hold,  this  product  being  divided  by  95.     For  two-deck  ves- 
sels the  rule  was  similar  except  that  one-half  the  breadth  was  sub- 
stituted for  the  measured  depth.     This  law  was  reenacted  in  1799 
and  remained  in  force  until   1864.     Aside  from  increasing  the 
number  of  transverse  sections  to  be  measured  in  calculating  under- 
deck  and  superstructure  capacity  the  Law  of  1864  was  exactly 
the  same  as  the  British  Law.     It  was  merely  a  gross  tonnage  law, 
however,   no   allowance  being1   made    for  engine-room  or   crew 
space  and  foreign  vessels  paid  tonnage  dues  upon  gross  tonnage 
until  1882.     In  1-865  the  law  was  passed  which  exempted  from 
measurement  passenger  cabins  above  the  uppermost  full  length 
deck  not  a  deck  to  the  hull.     In  1882  net  tonnage  was  made  the 
basis  for  tonnage  taxes  and  the  Danube  rule  was  authorized  for 
deducting  propelling-power  space.     The  allowable  deductions  for 
spaces  above  decks  were  increased  in  1895,  and  the  British  rule 
for  propelling-power  deductions  substituted  for  the  Danube  rule. 

The  Commissioner  of  Navigation  has  supervision  over  the 
measurement  of  vessels  and  the  law  requires  that  the  vessel  "  shall 
be  measured  by  a  surveyor,  if  there  be  one,  at  the  port  or  place 
where  the  vessel  may  be,  and  if  there  be  none,  by  such  person 
as  the  collector  of  the  district  within  which  she  may  be  shall  ap- 
point." In  practice  this  work  is  now  done  by  men  in  the  marine 
divisions  in  the  custom  houses,  some  of  whom  leave  their  tariff 
figures  or  statistical  compilations  to  perform  it.  Necessarily  their 
qualifications  vary  widely,  and  to  promote  uniformity  only  one 
adjuster  is  provided  at  a  remuneration  of  $3500  per  annum,  in- 
cluding expenses.  During  the  recent  expansion  in  shipbuilding 
the  appropriation  for  measurement  purposes  would  have  been  in- 
sufficient had  it  not  been  for  the  constancy  to  type  of  many  of  the 
vessels  on  the  Shipping  Board  program.  This  inefficient  method 
of  handling  measurement  is  in  startling  contrast  to  the  provision 
made  in  some  foreign  countries. 

4.  Suez  Canal  Company. —  The  Suez  Canal  was  opened  for 
navigation  in  1869,  and  its  franchise  gave  it  the  privilege  of  col- 
lecting toll  from  all  vessels  passing  through.  The  tolls  were  first 


206  MERCHANT  VESSELS 

collected  upon  the  ship's  national  tonnage  as  shown  by  its  papers. 
In  1872  the  English  gross  tonnage  was  substituted  as  a  basis  for 
tolls,  which  led  to  international  disputes  and  the  creation  of  an 
International  Tonnage  Commission  in  1873.  In  l&74  tne  com- 
pany was  compelled  by  military  force  to  adopt  the  Commission's 
rules,  and  in  1876  they  were  accepted.  In  1878  the  British  gov- 
ernment obtained  the  practical  exemption  of  certain  deck  spaces, 
and  in  1899  it  was  agreed  that  deck  spaces  excluded  by  British 
rules  would  be  so  treated  at  Suez,  but  would  be  taxed  when  found 
carrying  merchandise  and  thereafter.  This  arrangement  was 
easily  evaded  by  shipowners,  and  in  1902  the  company  agreed  to 
exempt  those  portions  of  shelter-deck  spaces  which  were  entitled 
to  it  because  of  their  openings  and  to  treat  isolated  deck  spaces 
by  the  rules  of  1897.  But  any  space  once  found  in  use  was  there- 
after to  be  measured.  In  1904  it  was  agreed  that  the  judgment 
of  the  Suez  surveyors  should  determine  whether  spaces  were 
open  or  closed,  and  at  the  present  time  deck  spaces  are  divided  into 
three  classes  and  treated  as  described  later  in  this  chapter. 

Certificates  of  tonnage  issued  by  the  regularly  appointed  officials 
of  the  various  countries  are  accepted  at  the  Suez  Canal,  subject 
to  the  inspection  and  interpretation  of  the  Canal  authorities. 

5.  Panama  Canal  Rules. —  An  act  of  Congress  in  1912  gave 
the  President  of  the  United  States  power  to  prescribe  the  tolls 
to  be  charged  vessels  using  the  Panama  Canal,  and  a  schedule 
was  issued  the  same  year.  The  Secretary  of  War  was  authorized 
to  make  the  necessary  rules,  and  these  were  prepared  by  Emory 
R.  Johnson,  Special  Commissioner  on  Panama  Canal  Traffic  and 
Tolls,  in  1913.  They  are  most  nearly  similar  to  the  Suez  Canal 
rules  and  provide  for  the  measurement  of  net  tonnage.  The 
gross  tonnage  includes  all  available  carrying  capacity  as  far  as 
possible  and  propelling-power  deductions  are  made  by  the  Danube 
rule.  Only  one  difficulty  has  arisen  in  the  administration  of  these 
rules.  The  law  required  that  the  tolls  should  be  not  more  than 
$1.25  per  net  registered  ton.  When  this  law  was  passed  the 
Panama  Canal  rules  were  not  in  existence  and  the  question  has 
been  raised  as  to  what  was  meant  by  net  registered  tonnage  when 
the  act  was  passed.  Not  the  net  registered  tonnage  by  Panama 
Canal  rules,  it  is  argued,  for  these  were  not  in  existence.  Ac- 
cordingly, it  is  the  practice  to  levy  tolls  on  Panama  Canal  rules 
at  $1.00  per  ton,  provided  the  tolls  collected  do  not  exceed  $1.25 


COMPARISON  OF  MEASUREMENT  RULES 


207 


per  net  ton  under  American  rules.  Two  sets  of  rules  are  there- 
fore in  actual  operation,  the  shipowner  receiving  the  benefit  of 
the  more  liberal  treatment.  Otherwise  these  rules  have  been  in 
use  for  seven  years  without  appreciable  difficulty  or  change. 

The  authorized  national  officials  may  issue  Panama  tonnage 
certificates,  subject  to  correction  by  the  officials  authorized  by  the 
President  to  administer  these  rules. 

SUMMARY  OF  MEASUREMENT 


Tonnage  deck 


I.     Methods  of  measurement 


Depth 
Breadth 


II. 


Spaces 
exempt 
from 
measure- 
ment 


Below  tonnage  deck 


. 


Above 

tonnage 

deck 


Hatches 


Because  of 
.purpose 


III.    Deductions 


GeneraL 


Openings  in  partitions 

Water  ballast 
Machinery  —  auxiliary 
boiler  ventilating  en- 
gine room 
Navigating 

Shelter  for  passengers 
Toilets 
Kitchens 
Bakery 

Companionways 
Skylights,  domes 
Hatches 

Crew  Toilets 
rCrew  Passageways 

Space  j  Crews  galley 

Captain's  quarters 

Steering 

Capstan  and  hoisting 


Navigating^ 


spaces 


Chart  room 


Boatswains  storeroom 
Auxiliary  boiler 
Sail  room 

fPrincipal  volume 
For  propelling  machinery  J  Ventilating  spaces 

[Shaft  tunnel 


208  MERCHANT  VESSELS 


Using  the  United  States  rules  described  in  previous  chapters 
as  a  basis,  it  will  be  instructive  to  compare  the  application  of 
these  five  rules  to  the  measurement  of  vessels,  indicating  the 
most  important  respects  in  which  they  differ,  the  reasons  for  cer- 
tain provisions,  and  their  deficiencies  in  some  respects.  Pre- 
liminary thereto  it  may  not  be  out  of  place  to  present  for  review 
the  outline  of  the  important  items  in  tonnage  mearusement  shown 
on  the  preceding  page. 

APPLICATION  OF  RULES 

Tonnage  Deck. —  The  national  and  canal  rules  all  agree  as  to 
what  shall  be  considered  the  tonnage  deck.  The  lower  deck  is 
often  replaced  by  beams  and  in  the  case  of  web-framed  vessels  is 
entirely  missing,  so  that  the  first  actual  deck  from  the  bottom  is 
considered  the  tonnage  deck.  Under  the  Panama  Canal  rules  a 
trunk  deck  or  turret  deck  is  considered  the  upper  deck  and  since 
the  vessel  has  but  two  decks  becomes  the  tonnage  deck.  The 
space  within  the  turret  or  trunk  is  measured  as  are  other  'tween- 
deck  spaces.  In  the  case  of  English  and  German  rules  the  width 
of  the  turret  where  it  meets  the  sides  is  taken  as  the  tonnage 
deck.  The  Suez  rules  calculate  separately  the  space  below  the 
tonnage  deck  and  the  turret  space,  in  a  fashion  similar  to  the 
British  rules.  For  trunk-decked  vessels  the  width  at  the  top  of 
the  sides  below  the  trunk  is  taken  as  the  location  of  the  tonnage 
deck  (see  page  84).  Under  the  British  rules  the  upper  deck  of 
the  self-trimming  vessel  is  used  as  the  tonnage  deck. 

Length. —  The  length  is  measured  in  the  same  manner  by  all 
five  systems. 

Tonnage-Length  Divisions. —  The  British,  German,  Suez,  and 
Panama  rules  classify  vessels  into  five  groups  according  to  length, 
dividing  the  tonnage  lengths  of  these  groups  into  4,  6,  8,  10,  and 
12  parts  respectively.  The  length  groups  have  similar  boundaries 
under  all  these  rules.  The  American  rules  differ  in  that,  as  seen 
in  a  preceding  chapter,  they  classify  vessels  according  to  length 
into  six  groups,  and  divide  the  tonnage  length  of  these  groups 
into  6,  8,  10,  12,  14,  and  16  parts  respectively.  The  United 
States  requirement  tends  toward  greater  accuracy  of  measure- 


COMPARISON  OF  MEASUREMENT  RULES  209 

ment,  but  the  results  have  been  considered  hardly  commensurate 
with  the  trouble  and  time  involved.  The  difference  caused  by 
measuring  20  sections  instead  of  12  would  not  often  amount  to 
i  per  cent  of  the  gross  tonnage.  The  Panama  Canal  measure- 
ment rules  of  1913  consequently  required  only  12  divisions  for 
the  largest  vessel. 

Measurement  of  Depths. —  The  Moorsom  system  is  followed 
universally,  and  consequently  the  same  depth  measurements  are 
required  by  all  rules.  When  a  ship  has  an  irregular  bottom 
line,  the  ship  is  divided  into  longitudinal  sections  at  the  points 
where  there  are  abrupt  changes  in  the  bottom  line.  In  the 
Suez  rules,  however,  there  appears  to  be  nothing  to  cover  this. 

Tonnage  under  the  Tonnage  Deck. — As  far  as  the  tonnage 
under  the  tonnage  deck  is  concerned,  it  is  apparent  that  all  of 
the  rules  are  in  substantial  accord  and  this  tonnage  for  a  given 
vessel  is  therefore  always  approximately  the  same. 

Between-Deck  Tonnage. —  The  method  of  measurement  is 
identical  under  all  the  rules,  but  there  is  no  agreement  as  to 
what  shall  be  measured  and  what  exempted.  The  discrepancy 
arises  from  the  different  interpretation  placed  upon  the  expres- 
sion "  permanently  closed-in "  and  similar  phrases,  interpreta- 
tions undeniably  colored  in  some  instances  by  the  desire  of  na- 
tions to  obtain  preferential  treatment  through  the  understate- 
ment of  gross  tonnage  and  consequently  net.  After  the  British 
Act  of  1854  permanent  closed-in  spaces  were  measured  until  1875. 
By  1860,  however,  vessel-owners  demanded  some  allowance  for 
superstructures  and  what  is  now  known  as  a  shelter  deck.  This 
was  originally  little  more  than  a  substantial  awning  built  above 
the  upper  deck,  and  as  such  the  space  below  was  exempt  from 
measurement,  but  the  natural  tendency  was  gradually  to  enclose 
this  space  as  far  as  possible  and  still  retain  the  exemption  from 
measurement.  In  1864  the  United  States  Measurement  Act  was 
adopted  and  naturally  followed  the  Moorsom  Act  and  the  then 
practice  of  the  British  Board  of  Trade  of  measuring  all  spaces 
sufficiently  closed  in  to  be  actually  available  for  cargo  or  pas- 
senger carriage.  In  1866,  due  to  disputes  with  shipowners,  the 
British  Board  of  Trade  proposed  that  spaces  under  the  shelter 
deck  should  not  be  measured  and  were  not  to  be  used  for  freight 
or  for  the  accommodation  of  crew  or  passengers,  a  proposal  which 
was  not  accepted;  whereupon  the  Board  of  Trade  proceeded  to 


210  MERCHANT  VESSELS 

measure  all  such  spaces.  The  shipowners  tested  the  legality  of 
such  measurement  in  the  courts.  Meanwhile  Germany  passed  a 
measurement  law,  in  1872,  which  embodied  the  same  provisions  in 
respect  to  shelter-deck  spaces  as  the  English  law  and  enforced 
the  same  strict  interpretation.  A  year  later  an  International  Com- 
mission framed  the  rules  for  the  Suez  Canal.  These  followed 
the  English  rules  with  respect  to  shelter-deck  spaces,  but,  in 
view  of  the  controversy  then  running  in  England,  closed-in  spaces 
were  accurately  defined  and  it  was  provided  that  shelter-deck 
space  should  be  measured  by  providing  that  "  openings  will  not 
prevent  measurement  if  the  openings  can  be  easily  closed  in 
after  measurement."  The  feelings  of  tonnage  experts  can  be 
imagined  when,  after  having  made  such  progress,  the  English 
House  of  Lords  decided  in  1875  that  it  was  illegal  to  measure  the 
space  under  the  shelter  deck  of  the  steamer  Bear.  The  reasoning 
was  that  the  cargo  between  this  covering  and  the  main  deck  was 
not  cargo  stowed  and  sealed  up  in  a  hold  but  was  deck  cargo 
protected  against  the  weather,  and  that  consequently  the  Bear  had 
not  a  third  deck.  In  1876,  however,  to  prevent  the  anomaly  of  a 
vessel's  actually  entering  port  with  a  cargo  in  the  space  exempted 
from  measurement,  an  act  was  passed  providing  that  if  cargo 
was  carried  in  any  unmeasured  space  the  space  actually  occupied 
by  cargo  should  be  measured  for  the  calculation  of  tonnage  dues. 
This  space  unoccupied,  however,  was  free.  The  Royal  Com- 
mission of  1881  recommended  the  measurement  of  shelter-deck 
space,  but  without  result.  The  present  British  instructions  ad- 
vise surveyors  to  "have  regard  to  the  character  and  structural 
conditions  of  such  deck  erections,"  not  to  measure  them  when 
they  have  "  one  or  more  openings  in  the  sides  or  ends  not  fitted 
with  floors  or  other  permanently  attached  means  of  closing  them," 
but  if  otherwise  "  so  closed  in  as  to  be  not  only  available  but 
also  actually  fitted  and  used  for  the  berthing  or  accommodation 
of  passengers,"  to  measure  them.  The  openings  in  the  shelter 
deck  must  be  of  prescribed  size. 

The  present  German  laws  were  adopted  in  1895  and  modified 
subsequently  several  times,  but  the  object  has  constantly  been 
to  make  the  tonnage  results  coincide  with  those  attained  under 
British  treatment,  so  -that  while  the  German  law  is  not  identically 
worded  the  results  have  become  in  practice  identical.  There  is, 
however,  no  deck  cargo  provision  in  Germany. 


COMPARISON  OF  MEASUREMENT  RULES  211 

The  Suez  rules  remained  as  strict  in  respect  to  shelter-deck 
space  as  they  were  originally  until  1899,  when  an  agreement  was 
unofficially  made  that  spaces  declared  open  under  British  measure- 
ment would  not  be  measured  unless  actually  used  to  stow  freight. 
Evasion  by  shipowners  brought  about  the  abandonment  of  this 
agreement  in  1902  and  the  Suez  regulations  of  1904  provided 
for  the  measurement  of  all  shelter-deck  space  except  that  in  the 
way  of  opposite  openings  in  the  side  plating  of  the  ship. 

The  Panama  rules  of  1913  follow  the  Suez  rules  as  modified  in 
1904  in  the  treatment  of  shelter-deck  space. 

The  following  illustration  shows  the  results  attained  through 
the  diversity  of  shelter-deck  treatment: 

THE  BRITISH  STEAMSHIP  Stephen 

Built  of  steel,  1910;  a  freight  steamer  with  accommodations  for  some 
passengers,  of  a  type  used  in  the  trade  between  New  York  and 
the  Amazon;  two  decks  and  a  shelter  deck;  coal  capacity  noo 
tons;  average  speed  around  n  knots;  registered  length,  376.4 
feet ;  registered  breadth,  50.3  feet ;  registered  depth,  23.6  feet. 


United  States 
Rules 

British 
Rules 

Suez 
Rules 

Under  tonnage 

deck  

7707.  ^6 

^607.^6 

^607.  ^6 

Between  decks 

etc.  .  .  I  

O/^/  •J~* 

1862.96 

OV-"-Y     J^r 
827.48 

1870.^4 

Gross  tonnaere 

<U70.32 

44^4.84 

"U77.70 

It  is  apparent  that  the  American  treatment  has  been  stricter 
than  the  British  or  German  but  does  not  equal  the  Panama  or 
Suez  interpretations. 

The  only  logical  method  of  handling  this  subject  is  strictly  to 
measure  all  space  actually  closed  in,  whether  theoretically  so 
closed  or  not.  Even  though  only  temporary  means  of  closing  are 
provided,  it  is  evident  that  these  spaces  are  intended  to  be  used 
for  cargo  when  cargo  is  available.  If  measured,  they  would 
probably  be  provided  with  permanent  means  of  closing,  and  it  is 
difficult  to  see  why  even  the  space  opposite  side  openings  should 
be  exempt. 

Method  of  Measuring  Between-Deck  Spaces. —  All  the  coun- 
tries employ  the  Moorsom  system,  the  length  being  divided  in 
accordance  with  the  division  of  the  tonnage  length  in  the  various 
countries  and  the  widths  being  taken  in  the  same  fashion  as  the 
widths  used  in  measuring  the  principal  volume. 


212  MERCHANT  VESSELS 

(Superstructures. —  The  differences  in  methods  of  measuring 
these  spaces  are  hardly  worth  noting.  The  Panama  rules  follow 
the  same  system  as  the  American  rules.  As  to  the  spaces  to  be 
measured  and  those  which  are  exempt,  however,  the  rules  differ 
greatly,  but  this  is  best  disposed  of  by  considering  seriatim  the 
various  exempted  spaces. 

Spaces  Exempt  below  the  Tonnage  Deck. —  There  are  no 
such  spaces  of  any  consequence  exempt  under  any  of  the  rules, 
with  the  exception  of  hatchways  and  passageways  (which  are 
best  considered  later),  and  double  bottoms.  The  latter  are  exempt 
under  all  the  rules  when  used  exclusively  for  water  ballast  and 
under  the  Suez  rules  are  always  exempt.  The  national  and 
Panama  rules  are  superior  to  the  Suez  rules  in  this  respect,  the 
latter  obviously  giving  considerable  advantage  to  oil-burning  ves- 
sels carrying  fuel  oil  in  double  bottoms. 

Water-ballast  tanks  other  than  in»double  bottoms  are  measured 
by  all  the  rules. 

Spaces  Exempt  above  the  Tonnage  Deck  because  Unen- 
closed.—  Hatchways  are  exempt  under  all  the  rules  up  to  y*  of 
i  per  cent  of  the  gross  tonnage ;  the  excess  above  this  is  measured. 
These  were  originally  insignificant  and  were  ignored  in  British 
measurement  but  later  they  increased  in  size  and  if  over  a  foot 
in  height  were  measured,  but  not  otherwise.  After  1876  all 
hatchways  were  measured  and  the  excess  referred  to  above  in- 
cluded in  the  gross  tonnage.  Permanent  erections  made  unavail- 
able for  cargo  or  passengers  by  reason  of  openings  are  exempt 
under  all  the  rules.  It  is  unnecessary  to  repeat  the  discussion 
of  the  interpretation  of  "  closed  "  spaces  but  the  method  of  treat- 
ing spaces  above  decks  under  the  present  Suez  rules  is  interest- 
ing. By  the  memorandum  of  1904  these  spaces  are  divided  into 
three  groups : 

1.  Spaces  considered  as  "closed"  under  the  national   rules. 
These  are  naturally  measured. 

2.  Spaces  considered  as  "  open  "  under  both  national  and  Suez 
rules,  which  are,  of  course,  exempt. 

3.  Spaces  considered  "  open  "  under  national  rules  and  "  closed  " 
under  Suez  rules.     The  1897  instructions  as  to  whether  a  space 
was  open  or  closed  were  suppressed  and  it  was  left  to  the  judg- 
ment of  the  surveyors  to  determine  from  experience  and  good 
sense  whether  or  not  a  deck  space  could  be  used  for  transport- 


COMPARISON  OF  MEASUREMENT  RULES  213 

ing  merchandise  other  than  deck  loads.  This  end  was  reached, 
however,  by  the  concession  that  certain  forecastle,  bridge  and  poop 
space  was  not  to  be  measured,  principally  that  portion  of  these 
structures  which  was  least  usable. 

Spaces  above  Tonnage  Deck  Exempt  because  of  Purpose. — 
These  include  spaces  unavailable  for  cargo  or  passengers  and 
mere  conveniences  for  the  latter. 

1.  Water-Ballast  Space. —  This  is  uncommon  above  the  tonnage 
deck  and  is  measured  by  all  rules,  though  usually  deducted  in 
ascertaining  net  tonnage  if  unavailable  for  the  carriage  of  cargo 
or  fuel.     Under  the  British  rules  the  water-ballast  space  at  the 
sides  of  a  self-trimming  vessel  is  exempt,  however. 

2.  Machinery   Spaces. —  Under  the   Suez   rules  this  space  is 
always  measured  and  deducted  later,  if  not  used  to  hoist  cargo. 
If  the  donkey  engine  and  boiler  are  below  decks  the  space  occupied 
is  measured  by  all  the  rules.     If  connected  with  the  engine  room 
it  is  later  deducted  under  all  the  rules  except  the  Suez  rules. 
The  latter  treatment  is  difficult  to  explain.     If  these  appliances 
are  above  decks  and  not  connected  with  the  engine  room  they 
are  exempt  under  the  American,  British,  and  German  rules,  for 
reasons  hard  to  see.     They  are  partly  used  for  navigating  pur- 
poses and  partly  for  cargo.     If  connected  with  the  engine  room 
they  are  measured  and  later  deducted  under  the  British,  German, 
and  American   rules.     Under  the   Suez  and   Panama  rules  the 
space  above  decks  is  always  measured,  and  if  exclusively  used 
for  navigation  and  not  for  hoisting  cargo  is  deducted,  which  is 
very  logical. 

From  the  accompanying  diagram  it  may  be  seen  that  a  closed- 
in  space  is  frequently  provided  above  the  crown  or  top  of  the 
engine-room  space  for  light  and  ventilation,  referred  to  hereafter 
as  light  and  air  space.  Under  the  American  rules  this  space  is 
not  added  to  the  gross  tonnage  unless  requested  by  the  owner  for 
the  purpose  of  adding  to  his  engine-room  space  and  consequently 
his  subsequent  engine-room  deduction.  In  Great  Britain,  prior 
to  1879,  light  and  air  spaces  from  the  crown  of  the  engine  room 
to  the  upper  deck  were  included  in  gross  tonnage  and  the  space 
so  measured  later  included  in  engine-room  deductions.  The  space 
of  similar  character  above  the  upper  deck  was  neither  included 
in  the  gross  tonnage  nor  deducted  later.  A  court  decision  in  the 
Isabella  case  in  1879  compelled  the  anomalous  deduction  of  such 


214  MERCHANT  VESSELS 

space  above  the  upper  deck  even  though  it  had  never  been 
measured.  This  was  not  corrected  until  1889.  when  it  was  pro- 
vided that  no  space  should  be  deducted  unless  previously  measured 
and  included  in  gross  tonnage.  It  was  also  provided  that  light 
and  air  spaces  above  the  upper  deck  should  not  be  measured 
except  at  the  request  of  the  owner.  The  owner  may,  however, 
have  measured  such  portion  of  such  space  as  may  be  desirable 
in  order  to  have  his  engine-room  deduction  brought  to  the  de- 
sired figure.  Under  the  American  rules  such  space  is  treated 
as  an  entirety  and  either  measured  or  not  as  the  owner  elects. 
The  German  rules  are  similar  to  the  British.  Under  the  Suez 
rules  the  light  and  air  space  is  measured  if  the  German  rule  for 
engine-room  deductions  is  followed,  and  if  the  Danube  rule  is 
used  the  owner  is  given  an  option.  If  such  spaces  are  measured 
and  consequently  included  as  engine-room  he  forfeits  certain  ex- 
emptions to  which  he  is  otherwise  entitled,  namely,  the  exemption 
of  open  spaces  which  may  exist  at  the  extremities  of  this  space, 
and  all  tiers  of  superstructures  below  the  tier  under  consideration 
are  measured  the  same  as  between-decks. 

Under  the  Panama  rules  the  spaces  that  are  framed  in  around 
the  funnels  and  the  spaces  for  light  and  air  are  included  in  the 
engine  room  to  the  extent  that  such  spaces  are  below  the  covering 
of  the  first  tier  of  side-to-side  erections,  if  any,  upon  the  upper- 
most full-length  deck,  whether  that  deck  is  or  is  not  fitted  with  a 
"  tonnage  opening."  The  spaces  above  the  deck  or  covering  of 
the  first  tier  of  side-to-side  erections  upon  the  uppermost  full- 
length  deck  are  exempted  from  measurement. 

The  treatment  under  the  Panama  rules  is  much  superior.  Un- 
der the  other  rules  similar  space  on  similar  vessels  will  be  some- 
times included  in  gross  tonnage  and  sometimes  exempt,  depend- 
ing on  the  ratio  of  engine  space  to  gross  tonnage  and  the  desire  of 
the  owner.  Under  the  British  rules  the  owner  may  still  further 
"  jockey  "  with  this  space,  treating  a  portion  of  it  in  one  fashion 
and  a  portion  in  another.  In  full-cargo  vessels  this  space  is 
likely  to  be  measured,  and  in  high-powered  passenger  vessels  ex- 
empted. 

3.  Navigating  Spaces. — The  spaces  for  the  anchor  gear,  steer- 
ing gear,  and  capstan  under  American,  British  and  German  rules 
are  included  in  the  gross  tonnage  when  situated  below  the  upper 
deck,  and  exempted  when  above  said  deck.  In  the  former  case, 


COMPARISON  OF  MEASUREMENT  RULES  215 

however,  they  are  subsequently  deducted,  giving  the  same  net 
result  as  if  they  had  never  been  measured;  but  this  method  of 
treatment  makes  gross  tonnage  incapable  of  exact  definition.  The 
Panama  rules  measure  and  deduct  such  spaces  no  matter  where 
located,  a  sound  and  consistent  policy  which  gives  a  gross  tonnage 
more  nearly  approximating  the  actual  closed-in  space.  The  Suez 
rules  are  hybrid  in  this  respect,  measuring  all  these  spaces  but 
deducting  only  those  located  above  decks. 

The  chart,  lookout,  and  signal  houses  are  measured  under  all 
the  rules  and  later  deducted.  The  wheelhouse  is  measured  under 
the  Suez  and  Panama  rules  and  also  deducted.  Under  the  United 
States,  British,  and  German  rules  the  wheelhouse  is  exempt, 
which  understates  the  gross  tonnage  by  that  amount. 

4.  Passenger  and  Crew  Accommodations. —  Cabins  and  state- 
rooms located  on  the  upper  deck  to  the  hull  and  above  are  included 
in  the  gross  tonnage  under  all  rules,  with  one  exception,  but  tem- 
porary arrangements  to  shelter  passengers  on  short  voyages  are 
exempted  with  the  consent  of  tonnage  officials.  To  be  exempt 
under  the  Panama  rules  such  shelters  must  have  no  connection 
with  the  body  of  the  ship  other  than  the  props  necessary  for  their 
support.  Under  the  Suez  rules  the  test  is  simply  whether  "  open*" 
or  "  closed-in."  The  exception  referred  to  is  that  described  in 
Chapter  X  —  the  United  States  exemption  of  passenger  space 
above  the  first  deck  which  is  not  a  deck  to  the  hull  —  an  inde- 
fensible and  probably  accidental  provision. 

Space  for  the  storage  of  sails  is  measured  under  all  rules  and, 
except  under  the  Suez  rules,  a  certain  maximum  portion  may  be 
deducted  for  sailing  vessels. 

Skylights  and  domes  are  exempt  under  all  rules. 

Galleys,  cookhouses,  condenser,  and  bakery  spaces  are  all  meas- 
ured under  the  Suez  and  Panama  rules,  wherever  situated,  and 
such  as  are  exclusively  for  the  officers  and  crew  may  be  de- 
ducted, wherever  situated.  Under  the  national  rules  they  are 
exempt  if  situated  above  decks  and  measured  if  below  decks,  but 
in  the  latter  case  subject  to  deduction. 

Companion  houses  are  exempt  under  all  rules,  except  when 
used  for  smoking  rooms  or  other  special  purposes. 

Passageways  are  measured  when  serving  measured  spaces  under 
all  the  rules  and  exempt  when  serving  exempted  spaces.  Under 
the  American  and  British  rules  they  may  be  deducted  when  serving 


216  MERCHANT  VESSELS 

deducted  spaces,  under  the  German  and  Panama  rules  they  may 
be  deducted  when  serving  the  quarters  of  officers  and  crew  exclu- 
sively, and  under  the  Suez  rules  they  may  be  deducted  only  when 
fitted  with  lockers,  hammocks,  etc.,  for  the  use  of  crew  and  officers 
and  serving  crew  and  officers'  quarters. 

Toilet  facilities  for  the  officers  and  crew,  under  American,  Brit- 
ish, and  German  rules  are  exempted  if  above  decks,  and  measured 
and  deducted  if  below  decks.  Under  the  Suez  and  Panama  rules 
all  such  spaces  are  measured  and  deducted  if  used  exclusivel)* 
for  officers  and  crew.  Under  the  Suez  and  Panama  rules  pas: 
senger  toilets  are  all  measured  and  not  deducted.  Under  the 
other  rules  they  are  measured  when  below  decks,  without  privilege 
of  deduction,  and  above  decks  i  toilet  per  50  passengers,  not  ex- 
ceeding a  total  of  12,  is  exempt. 

While  some  are  technically  measurable  because  serving  pas- 
sengers, it  is  questionable  whether  in  the  interest  of  public  health 
all  these  spaces  should  not  be  exempt  from  measurement  or  at 
least  deducted.  They  contribute  little  or  nothing  extra  toward 
earning  capacity,  and,  on  the  other  hand,  contribute  greatly  to 
health,  comfort,  and  safety  of  passengers,  officers,  and  crew. 

Measurement  of  Propeller-Power  Space. —  The  tonnage  of 
the  engine  room  is  considered  to  include  the  following: 

1.  Space  below  the  crown  of  the  engine  room. 

2.  Space  between  the  crown  and  the  upper  deck  framed  in  for 
the  machinery  or  for  the  admission  of  light  and  air. 

3.  Space  similarly   framed  in  above  the  upper  deck.1 

4.  The  contents  of  the  shaft-trunk  or  trunks  in  screw  vessels. 

The  spaces  above  referred  to  are  measured  in  similar  fashion 
by  all  the  rules ;  the  product  of  the  mean  length,  breadth,  and 
depth  divided  by  100  being  considered  the  cubic  capacity.  Other 
spaces  jutting  into  these  volumes  and  not  strictly  a  part  thereof 
are  deducted. 

Necessity  for  an  Arbitrary  Rule. —  It  has  been  previously 
shown  that  while  the  space  occupied  by  fuel  is  very  considerable 
it  is  indeterminate  and  changing,  varying  with  the  stage  of  the 
voyage,  length  of  voyage,  possibility  of  recoaling,  efficiency  of 
the  machinery,  quality  of  fuel,  quantity  of  cargo,  character  of  the 
trade,  and  other  factors.  The  space  occupied  by  fuel  cannot 

1  Reference  to  the  Panama  rules  in  this  respect  is  made  later. 


COMPARISON  OF  MEASUREMENT  RULES  217 

be  accurately  measured,  therefore  it  must  be  assumed  that  it 
varies  with  some  other  characteristic  or  characteristics  of  the 
vessel,  such  as  the  engine-room  space. 

THREE  PRO  FELLING- POWER  RULES 

i.  The  Percentage  Method. —  This  rule  originated  in  Great 
Britain.  The  British  Act  of  1819  allowed  for  engine-room  space 
by  deducting  the  length  of  the  engine  room  from  the  length  of 
keel  to  determine  the  tonnage  length.  The  Act  of  1836  provided 
that  the  actual  space  occupied  by  the  engine  room  should  be  de- 
ducted from  the  gross  tonnage.  The  1819  rule  was  probably  not 
far  from  correct  for  vessels  of  only  two  or  three  decks,  but  the 
1836  rule  was  taken  undue  advantage  of  by  the  construction  of 
vessels  with  engine  and  boiler  room  separated.  The  space  be- 
tween was  not  used  for  machinery  or  fuel  but  was  included  in  the 
engine-room  deduction  because  the  space  between  the  forward  and 
after  bulkheads  bounding  the  engine  and  boiler  rooms  was  taken 
for  this  purpose.  Moorsom  was  in  favor  of  continuing  this  sys- 
tem on  a  practicable  basis  in  the  Act  of  1854,  but,  instead,  the  so- 
called  percentage  rule  was  inserted.  Confining  attention  to  the 
screw-propelled  vessels  the  rule  is:  When  the  boiler  and  machin- 
ery space  is  above  13  and  under  20  per  cent  of  the  gross  tonnage 
of  the  ship,  the  deduction  for  the  same  shall  be  32  per  cent  of 
the  gross  tonnage.  As  regards  all  other  ships,  the  deduction,  if 
the  Board  of  Trade  and  the  owner  agree,  shall  be  estimated  in  the 
same  manner,  but  either  they  or  he,  in  their  or  his  discretion,  may 
require  the  engine-room  space  to  be  measured  and  a  deduction  to 
be  made  of  1^4  times  the  tonnage  of  such  space.  In  1860  the 
Board  of  Trade,  acting  upon  the  authority  of  a  law  which  gave 
it  power  to  make  modifications  of  the  tonnage  rules  for  the  "  more 
accurate  and  uniform  application  thereof  and  the  effectual  carrying 
out  of  the  principle  of  admeasurement  therein  adopted,"  substi- 
tuted for  the  percentage  rule  the  rule  of  1836.  In  1866  the  courts, 
upon  application  by  a  vessel  owner,  held  that  the  Board  of  Trade 
had  exceeded  its  authority  and  the  percentage  rule  regained  the 
place  it  has  since  held.  As  to  vessels  with  engine-room  space  ag- 
gregating 13  per  cent  or  less  of  the  gross  tonnage  and  those 
with  similar  space  totaling  20  per  cent  or  over,  the  Danube  rule 
is  applied  in  the  former  case  by  the  Board  of  Trade's  option  and 


218 


MERCHANT  VESSELS 


in  the  latter  because,  being  more  favorable,  it  is  assumed  to  be 
the  owner's  desire.  An  act  of  1907  restricted  the  total  deduction 
for  propelling  power  in  any  case  to  55  per  cent  of  the  vessel's 
tonnage  remaining  after  other  deductions  than  those  for  propel- 
ling power  have  been  made.  Such  is  the  present  rule  in  Great 
Britain.  We  will  defer  the  discussion  of  the  percentage  rule  and 
examine  the  Danube  rule,  which  forms  part  of  the  British  and 
American  systems. 

2.  The  Danube  Rule. —  This  rule  had  also  a  British  origin.  It 
was  part  of  the  law  of  1854,  as  described  above,  is  part  of  the 
law  to-day,  and  efforts  have  been  made  there  to  make  it  the  sole 
rule  for  propelling-power  deductions.  But  the  great  majority  of 
British  vessels  come  within  the  percentage-rule  portion  of  the 
law.  This  part  of  the  British  system  was  rejected  by  the  Euro- 
pean Commission  of  the  Danube,  an  international  commission 
established  by  the  Treaty  of  Paris  in  1856,  to  control  the  Danube 
River.  The  Commission  established  as  its  exclusive  rule  for  pro- 
pelling-power deductions  the  following:  The  deduction  for  pro- 
pelling power  shall  be  \Y\  times  the  actual  volume  of  the  engine 
room  (150  per  cent  for  paddle-wheel  steamers).  The  rule  was 
consequently  known  as  the  Danube  rule. 

RATIO    OF    ENGINE-ROOM    SPACE    TO    GROSS    TONNAGE 


13  per  cent  or 
under 

14  per  cent 
to 
19  per  cent 

20  per  cent 
or  over 

Maximum 

United 
States 

Danube 

percentage 

Danube  or 
percentage 

none 

Great 
Britain 

Danube  or 
percentage 

percentage 

Danube  or 
percentage 

55  per  cent  of 
gross  tonnage 
after  other  de- 
ductions 

Germany 

Danube  * 

percentage 

Danube  or 
percentage  t 

none 

Suez 

For  vessels  without  fixed  bunkers,  the 
Danube  rule  ;  for  all  others  the  German  or 
Danube  f 

50  per  cent  of 
gross  tonnage 

Panama 

Danube  for  vessel  without  fixed  bunkers 
and  for  all  others  the  German  f 

50  per  cent  of 
gross  tonnage 

*  Unless  the  bureau  of  registry  requires  the  percentage  rule. 
t  Choice  of  the  owner. 

COMPARISON  OF  MEASUREMENT  RULES  219 

3.  The  German  Rule. —  Like  the  -two  preceding  rules  this  rule 
had  a  British  origin,  being  the  rule  contained  in  the  Act  of  1836 
and  recommended  by  the  Board  of  Trade  in  1867.  It  was  adopted 
by  Germany  in  1873,  whence  the  name.  This  rule  provides  for 
the  deduction  of  the  space  actually  occupied  by  the  engine  room 
and  fixed  bunkers  or  oil  compartments. 

The  preceding  table  summarizes  the  treatment  of  propelling- 
power  deductions  under  the  five  laws. 

DISCUSSION  OF  DEDUCTIONS  FOR  PROPELLING  POWER,  CREW 
SPACE,  AND  NAVIGATING  SPACE 

Propelling  Power. —  The  German  rule  may  be  quickly  disposed 
of  because,  since  it  measures  the  actual  capacity  of  the  engine 
and  fuel  spaces,  it  is  obviously  equitable  if  applied  alone.  Its, 
principal  function  in  existing  laws,  indeed,  is  to  provide  the  vessel 
owner  with  a  recourse  in  case  other  provisions  appear  .burdensome. 
It  is,  however,  applicable  only  to  vessels  with  fixed  bunkers,  and 
for  reasons  previously  explained  these  are  necessarily  rare,  so  that 
its  application  is  greatly  restricted.  The  history  of  the  percentage 
rule  in  Great  Britain  has  been  given  previously.  This  rule  was 
introduced  into  the  law  of  1854  under  protest  of  Moorsom.  and 
since  he  had  a  wholly  scientific  interest  in  the  subject  of  measure- 
ment, this  gave  a  prevision  of  its  probable  workings.  The  rule 
was  unsatisfactory  to  the  Board  of  Trade,  and  after  appeal  to 
Parliament  the  Board  of  Trade  took  upon  itself  the  responsibility 
of  substituting  another  system,  with  the  unfortunate  result  pre- 
viously described.  The  Danube  Commission  rejected  the  percent- 
age rule  with  the  full  approval  of  the  British  representatives.  Ef- 
forts to  repeal  it  were  made  in  1871,  1872,  1874  and  1881.  It  was 
condemned  by  the  English  Tonnage  Commission  of  1881.  By 
the  law  of  1907  the  amount  of  the  propelling-power  deduction  was 
limited  to  a  maximum  of  55  per  cent  of  the  tonnage  remaining 
after  the  other  deductions  had  been  made.  This  served  to  prevent 
a  vessel  having  a  negative  net  tonnage,  a  result  possible  previously. 
A  select  committee  appointed  by  the  Board  of  Trade  in  1906 
considered  that  sufficiently  strong  reasons  for  a  change  did  not 
exist  at  that  time,  but  the  expert  members  of  the  committee  dis- 
sented from  this  view.  A  Parliamentary  committee  was  appointed 
in  1907  and  recommended  the  law  above  referred  to,  limiting  the 


220  MERCHANT  VESSELS 

total  possible  deduction  for  engine-room  space.  Everything  was 
done  except  to  apply  the  remedy  —  the  repeal  of  the  law.  The 
objections  to  the  percentage  system  may  be  listed  as»  follows: 

1.  It  assumes  a  relationship  between  the  space  occupied  by  en- 
gine, boiler  and  fuel,  and  the  gross  tonnage  of  the  vessel,  which  is 
fallacious.     Even  though  such  a  relation  did  normally  exist,  the 
law   provides   an   incentive   for   the   vessel-owner   arbitrarily   to 
nullify  such  -relationship  by  unnecessarily  increasing  the  engine- 
room  space,  as  shown  later.     Thus  the  assumed  relationship  is 
vitiated  by  both  economic  and  legal  reasons. 

2.  The  deduction  allowed  always  exceeds  the  actual  space  oc- 
cupied and  so  violates  the  principle  that  the  net  tonnage  should 
represent   the   earning'  capacity.     The   Danube   rule   admittedly 
makes  a  liberal  allowance  for  this  purpose.     In  an  8ooo-ton  vessel 
with  engine-room  tonnage  of  1120,  the  allowance  under  the  Danube 
rule  would  be  1960  tons,  and  under  the  percentage  rule  2560  tons. 
In  ocean-going  steamers  the  actual  stowage  space  available  ex- 
ceeds the  net  tonnage  by  from  10  to  12  per  cent.     In  fact,  the 
percentage  rule  was  merely  an  attempt  to  favor  British  tonnage, 
which  in  self-defense  has  been  copied  by  other  nations. 

3.  The  percentage  rule  causes  space  on  the  vessel  to  be  wasted 
merely  for  the  purpose  of  enlarging  the  engine-room  sufficiently 

'to  qualify  for  the  32  per  cent  deduction.  In  a  io,ooo-ton  vessel, 
for  example,  if  the  engine-room  and  shaft  space  total  1200  tons 
the  owner  is  allowed  a  deduction  of  2100  tons.  By  increasing 
the  propelling-power  space  to  1400  tons,  however,  the  deduction 
is  increased  to  3200  tons,  or,  in  other  words,  an  increase  of  16% 
per  cent  in  propelling-power  space  carries  with  it  an  increase  in 
deduction  of  over  50  per  cent.  The  object  of  the  shipowner 
naturally  is  to  have  his  engine-room  space  always  exceed  13  per 
cent  but  by  as  small  a  margin  as  possible.  It  was  testified  that  in 
one  instance  it  was  necessary  to  break  down  the  engineer's  store- 
room and  put  a  partial  bulkhead  and  grating  in  front  of  it,  so  as 
to  allow  just  a  little  more  space  in  the  engine  room  to  qualify 
for  the  32  per  cent  deduction. 

4.  It  has  already  been  shown  that  the  option  allowed  for  light 
and  air  space  permits  the  owner  to  use  this  space  as  exempted 
space  or  as  engine-room  space.     Under  the  British  rules  he  can 
even  use  a  portion  of  the  space  as  he  desires.     This  further  com- 
plicates the  situation  by  introducing  another  variable  factor  into 


COMPARISON  OF  MEASUREMENT  RULES  221 

the  propelling-space  deduction.  The  volume  of  light  and  air 
space  may  be  arbitrarily  increased  in  order  to  obtain  the  benefit 
of  the  percentage  rule.  The  amount  of  all  propelling  space,  in- 
cluding light  and  air  space,  therefore  is  related  not  solely  to  the 
room  occupied  by  machinery  but  to  the  gross  tonnage  of  the  ves- 
sel as  well. 

5.  The  percentage  rule  discriminates  between  vessels.     Thus, 
in  three  Soooton  vessels,  the  first  with  engine-room  space  of  1020 
tons  would  be  entitled  to  a  deduction  of  1785  tons,  the  second  with 
engine-room  space  of  1060  tons  would  be  entitled  to  a  deduction 
of  2560  tons,  and  the  third  with  engine-room  space  of  1580  tons 
would  be  entitled  to  a  deduction  of  2560  tons.     One  or  more  of 
these  vessels  are  comparatively  unjustly  treated.     Secondly,  the 
rule  makes  no  distinction  as  regards  length  of  voyage,  although 
a  vessel  making  short  runs  is  using  much  less  space  for  fuel  and 
has  available  much  more  for  cargo  than  a  vessel  making  long 
ocean  voyages.     Thirdly,  the  rule  discriminates  between  high- 
and    low-speed   vessels    and   consequently   between    freight    and 
passenger  ships.     A  I2,ooo-ton  passenger  vessel  with  2280  tons 
of  propelling-power  space  would   receive  3840  tons   deductipji,^ 
while  a  I2,ooo-ton  freight  steamer  with  1680  tons  of  propelling- 
power  space  would   receive  the  same   allowance  of   3840  tons, 
in  spite  of  the  fact  that  the  former  high-speed  vessel  naturally 
requires  more  machinery  space  and  more  fuel  than  the  latter, 
which  can  steam  at  the  most  economical  speed.     It  is  true  that 
the  great  bulk  of  vessels  have  from  13.1  to  19.9  per  cent  of  their 
gross  tonnage  devoted  to  space  of  this  character,  but  even  within 
this  group  there  are  discriminations,  and  a  rule  which  is  favorable 
to  the  majority  is  still  not  equal  to  one  which  is  equitable  to  all. 
Though  this  is  now  a  comparatively  unimportant  matter,  it  might 
be  pointed  out  that  the  rule,  being  unduly  favorable  to  certain 
types  of  steamships,  discriminates  against  the  sailing  vessel. 

6.  The  effects  of  the  rule,  instead  of  being-  minimized  by  the 
passage  of  time,  have  been  aggravated.     With  the  increase  in 
the  number  of  decks  the  gross  tonnage  has  increased  in  compari- 
son with  the  engine-room  space,  so  that  the  allowance  has  tended 
to  exceed  the  latter  by  an  ever-increasing  margin.     The  increasing 
efficiency  of  the  marine  engine,  giving  greater  power  per  unit 
of  size  has  further  tended  to  increase  the  ratio  of  gross  tonnage  to 
engine-room  space.     Internal-combustion  engines  will  further  ac- 


222  MERCHANT  VESSELS 

centuate  this  tendency.  More  efficient  propelling  machinery  re- 
quires less  fuel  per  unit  of  work  done,  and  the  already  too  liberal 
allowance  for  fuel  space  becomes  still  more  excessive.  Increased 
coaling  facilities  decrease  the  average  supply  on  hand  and  free 
additional  space  for  carrying  cargo  which  has  been  deducted  for 
propelling  purposes. 

The  Danube  rule  is  apparently  more  scientific  and  equitable, 
and,  in  the  absence  of  accurate  measurement  of  fuel  space,  must 
be  accepted  as  the  best.  It  is  open  to  four  objections: 

1.  It  assumes  a  relationship  between  machinery  space  and  fuel 
space.     While  in  general  this  is  probably  true,  there  are  many  ex- 
ceptions, the  fuel  space  depending  upon  the  length  of  voyage  and 
distance  between  coaling  stations  also. 

2.  While  superior  to  the  percentage  rule,  the  Danube  rule  also 
violates  the  principle  of  making  the  net  tonnage  represent  earning 
capacity.     For  many  vessels  engaged  in  coasting  and  short  sea 
voyages   the    fuel    space   required    falls   considerably   below    75 
per  cent  of  the  machinery  space.     Even  as  regards  ocean  steamers, 
if  this  proportion  was  accurate  in  1854  it  cannot  be  at  the  present 
time,  in  view  of  the  improvements  which  have  taken  place. 

3.  Like  the  percentage  rule,  this  rule  does  not  improve  with 
time.     Many  of  the  important  changes  in  marine  propulsion  are  de- 
signed to  reduce  the  fuel  consumption,  and  the  fuel  space  has  been 
reduced  much  faster  than  the  machinery  space.     Take  for  example 
an  oil-burning  steamer.     The  space  required  for  the  machinery 
is  but  little  less  than  for  a  coal-burning  engine  but  the  oil  fuel 
requires  only  60  per  cent  of  the  space  required  for  coal. 

4.  Without  attempting  to  reach  a  decision  or  propose  a  remedy, 
it  is  pertinent  to  inquire  whether  the  enforcement  of  the  Danube 
rule  with  the  same  percentages  as  used  for  coal-burning  steamers 
will  not  create  an  unfortunate  precedent  which  will  be  as  hard  to 
eliminate  in  the  future  as  the  percentage  rule  has  been  in  the  past. 
Knowing  that  the  fuel  required  for  oil-burning  and  internal-com- 
bustion  engines   occupies   much   less   than   75    per   cent   of   the 
machinery  space,  why  accustom  the  owners  of  these  types  of 
vessels  to  a  too  liberal  allowance  which  they  will  demand  for  a 
long  time  to  come  ?    Furthermore,  the  Danube  rule  applied  indis- 
criminately   to    coal    and    oil-burning    vessels    will    discriminate 
against  the  former  to  a  considerable  degree,  thus  adding  to  the 
oil-burner's  possible  economic  advantage  an  artificial  legal  subsidy. 


COMPARISON  OF  MEASUREMENT  RULES  223 

In  framing  the  Panama  Canal  rules  in  1913  the  question  of 
adapting  the  propelling-power  deduction  rule  to  newer  methods 
of  propulsion  was  considered,  or  rather  the  question  of  choosing 
between  existing  rules  in  the  light  of  such  newer  methods.  In  the 
oil-burning  vessel  the  machinery  space  is  approximately  the  same 


FIG.  67 

as  for  a  coal-burner,  while  the  fuel  space  required  is  considerably 
less.  But  the  fuel  space  saved  is  not  entirely  available  for  cargo, 
inasmuch  as  the  space  which  would  have  been  occupied  by  coal 
bunkers  is  not  always  usable  for  cargo.  In  a  specially  constructed 
vessel,  however,  a  considerable  portion  of  this  space  would  be 
converted  into  usable  space.  Furthermore,  if  the  fuel  oil  is  carried 
in  double  bottoms  the  net  tonnage  is  increased  by  the  amount  of 
space  so  used,  under  the  Panama  rules.  In  view  of  these  facts 
the  Danube  rule  was  felt  to  be  satisfactory,  an  opinion  in  which 


224  MERCHANT  VESSELS 

the  writer  cannot  fully  concur.  In  the  internal-combustion  oil 
engine  type  of  carrier  there  is  a  very  considerable  reduction  in 
machinery  space  and  a  still  greater  reduction  in  fuel  space.  Un- 
der the  existing  national  rules  the  saving  in  machinery  space 
would  not  always  be  taken  advantage  of,  because  of  the  necessity 
of  bringing  the  engine-room  space  up  to  at  least  over  13  per 
cent  of  the  gross  tonnage.  The  reduction  in  fuel  space  leads  to 
a  great  increase  in  dead-weight  capacity.  In  the  internal-com- 
bustion gas  engine  there  is  very  little  saving,  if  any,  in  machinery 
space,  and  the  saving  in  fuel  space  is  not  equal  to  the  internal- 
combustion  oil  engine.  The  conclusions  reached  in  the  prepara- 
tion of  the  Panama  rules  were : 

1.  The  use  of  fuel  oil  increases  the  gross  and  net  tonnage  of 
the  vessel  under  the  Panama  rules,  which  partially  offsets  the 
saving  in  fuel  space. 

2.  The  difference  in  fuel  space  between  the  oil-burning  and 
coal-burning  steamer  is  not  deemed  great  enough  to  necessitate 
the  immediate  adoption  of  a  special  rule  applying  only  to  the 
comparatively  small  number  of  vessels  now  (1913)  equipped  with 
oil-burning  steam  engines. 

3.  The  number  of  large  merchant  vessels  equipped  with  internal 
oil-combustion  engines  is  still  comparatively  small    (1913),  the 
engine  is  still  in  the  process  of  development,  and  it  is  not  yet 
certain  whether  the  vaporized,  oil-gas,  producer-gas,  four-cycle 
Diesel,  two-cycle  single-acting  Diesel,  or  two-cycle  double-acting 
Diesel  will  prove  superior. 

4.  It  would  be  difficult,  at  the  present  time  (1913),  to  arrive 
at  a  general  average  ratio  of  fuel  space  to  machinery  space  for 
internal-combustion  engines  of  different  types. 

5.  Liberal  propelling-power  deductions  will  be  of  assistance  in 
bringing  more  promptly  into  service  marine  engines  of  the  greatest 
efficiency  and  economy. 

Crew  Space. —  Under  the  American  rules  the  sleeping,  dining, 
and  toilet  space  for  the  crew  was  deducted  from  the  gross  ton- 
nage, except  when  used  by  or  for  passengers.  A  minimum  space 
of  from  72  to  100  cubic  feet  and  from  12  to  16  superficial  feet 
per  seaman  is  required  by  law.  Under  the  British  rules  a  mini- 
mum of  120  cubic  feet  and  15  superficial  feet  is  required,  under 
the  German  rule  a  minimum  of  3.5  cubic  meters  and  1.5  super- 
ficial meters.  Under  the  Panama  rules  each  of  the  above  spaces 


COMPARISON  OF  MEASUREMENT  RULES  225 

is  subject  to  the  minimum  and  marking  requirements  of  the  navi- 
gation laws  of  the  several  countries.  These  spaces  are  deducted 
under  all  the  rules  with  the  following  exceptions.  Under  the 
British,  American  and  German  rules  galleys,  condenser  space, 
cook  houses,  and  bakeries  are  deducted  if  below  decks  but  not  if 
above  decks,  because  the  latter  were  exempt  from  measurement 
and  not  included  in  the  gross  tonnage.  Under  the  Panama  rules 
all  crew  space,  wherever  situated,  is  measured  and  consequently 
deducted.  Under  the  Suez  rules  all  such  space  is  measured  and 
deducted  if  used  exclusively  for  officers  and  crews.  Toilets  for 
the  crew  are  exempt  if  above  decks  and  consequently  are  not 
deducted,  while  those  below  decks  are  deducted  if  exclusively  so 
used,  under  British,  American,  and  German  rules.  Under  the 
Suez  and  Panama  rules  all  such  space  is  measured  and  deducted 
if  used  exclusively  for  officers  and  crew.  Passageways  are  de- 
ducted when  serving  other  deducted  spaces  exclusively  under  all 
the  rules  except  the  Suez,  where  they  are  not  deducted  unless 
fitted  with  lockers,  hammocks,  etc.,  for  use  of  crew  or  officers  and 
serving  crew  and  officers'  quarters.  The  master's  cabin  is  deducted 
under  all  the  rules  except  the  Suez.  This  is  true  also  of  the 
doctor's  cabin,  which  under  the  Suez  rules  must  be  actually  occu- 
pied by  the  doctor. 

Navigating  Spaces. —  These  consist  of  allowances  for  the  an- 
chor, steering  gear,  capstan,  wheelhouse,  chart  house,  lookout 
house,  signal  house,  sail  room,  boatswains'  stores,  and  donkey 
engine  and  boiler.  Under  British,  German,  and  American  rules 
the  anchor,  steering  gear,  capstan,  and  wheel  house  space  are  de- 
ducted if  below  decks  and  not  deducted  if  above  decks  because 
exempted.  Under  the  Suez  rules  such  spaces  are  deducted  if 
above  decks  and  not  deducted  if  below  decks.  Under  the  Panama 
rules  all  such  spaces  are  deducted.  Chart,  lookout,  and  signal 
spaces  are  deducted  under  all  rules.  Space  for  the  storage  of 
sails  in  sailing  vessels  is  deducted  under  all  rules  except  Suez, 
up  to  2l/2  per  cent  of  the  gross  tonnage.  Under  the  Suez  rules  no 
deduction  is  provided  for.  Boatswains'  stores  are  deducted  under 
all  rules  except  the  Suez,  but  under  the  Panama  rules  this  deduc- 
tion is  limited  to  I  per  cent  of  the  gross  tonnage  for  vessels  of 
1000  tons  or  over  and  to  75  tons  for  any  vessel.  Space  taken  by 
donkey  engine  and  boiler  is  measured  under  all  the  rules  if  below 
decks,  and  if  connected  with  the  engine  room  it  is  deducted  under 


226  MERCHANT  VESSELS 

all  the  rules  except  the  Suez.  If  above  decks  this  space  is  meas- 
ured and  deducted  by  the  German,  British,  and  American  rules 
if  connected  with  the  engine  room.  If  not  so  connected  it  is 
exempted.  Under  the  Suez  and  Panama  rules  such  space  is 
always  measured  and  if  the  engine  is  used  for  handling  cargo  is 
not  deducted;  otherwise  deducted. 

Under  the  German  and  Suez  rules  the  allowances  for  deduc- 
tions other  than  for  propelling-power  space  are  limited  to  5  per 
cent  of  the  gross  tonnage;  under  the  other  rules  they  must  merely 
be  reasonable  in  extent. 

With  respect  to  crew  and  navigation  spaces  the  Panama  rules 
are  superior  to  the  other  rules  because,  as  has  been  probably  no- 
ticed, they  consistently  include  such  spaces  in  the  gross  tonnage 
and  deduct  them  in  order  to  arrive  at  the  net  tonnage.  Under  the 
other  rules  these  spaces  are  treated  with  lamentable  confusion, 
though  the  net  differences  in  tonnage  as  a  result  are  negligible. 

INTERNATIONAL  TONNAGE 

The  first  instance  of  anything  approaching  international  uni- 
formity in  tonnage  was  in  1860,  when  the  Danube  Commission 
adopted  the  English  tonnage  of  1854  as  a  basis  for  tolls.  Factors 
were  used  to  convert  tonnage  reached  by  other  national  rules  into 
its  English  equivalent.  The  British  law  of  1862  provided  that 
when  any  foreign  nation  adopted  the  British  system  of  measure- 
ment the  tonnage  of  vessels  as  stated  in  its  official  papers  would 
be  accepted  at  British  ports  without  remeasurement.  The  British 
government  accordingly  urged  other  nations  to  adopt  the  British 
system  in  furtherance  of  uniformity  and  a  commission  was  ap- 
pointed in  France,  of  which  the  results  were  nil.  As  a  consequence 
of  the  British  law,  however,  the  Moorsom  system  and  the  Moor- 
som  ton  were  adopted  by  the  United  States  in  1865  and  by  Den- 
mark in  1867.  From  this  time  on  it  became  the  practice  to  enter 
into  reciprocal  tonnage  agreements  by  which  the  measurements  of 
foreign  countries  were  recognized  by  the  home  nation.  While 
other  nations  were  attempting  to  adapt  their  measurements  to  the 
existing  British  system,  however,  the  British  courts  handed  down 
the  decision  previously  described,  whereby  the  action  of  the 
Board  of  Trade  in  1860  respecting  engine-room  deductions  was 
held  to  be  illegal,  and  other  nations  began  to  modify  their  rules 


COMPARISON  OF  MEASUREMENT  RULES  227 

in  self-protection.  In  1871  the  Danube  Commission  gave  up  the 
English  rules  and  adopted  its  own  rules  for  engine-space  deduc- 
tions and  in  1876  adopted  the  Suez  rules.  In  1873  tne  Interna- 
tional Tonage  Commission  met  at  Constantinople  and  formulated 
the  rules  subsequently  known  as  the  Suez  rules,  which  were 
primarily  designed  as  a  basis  for  international  agreement.  England 
again  disappointed  the  hopes  of  international  uniformity,  however, 
by  failing  to  adopt  these  rules  in  1874.  Because  of  the  dominant 
position  of  Great  Britain  other  nations  felt  obliged  to  adopt  those 
rules  to  which  she  insisted  upon  adhering.  Italy  adopted  the 
percentage  rule  for  propelling-power  deductions  in  1882 ;  Japan, 
in  1884;  Norway,  in  1893;  Denmark,  Germany,  and  the  United 
States,  in  1895 ;  Holland,  in  1899;  Russia,  in  1900;  Spain,  in  1902; 
France,  in  1904.  Meanwhile  the  Moorsom  system  and  the  Moor- 
som  ton  had  been  adopted  by  the  following  countries : 

United  States 1865  Netherlands 1876 

Denmark 1867  Norway    1876 

Austria-Hungary   1871  Argentina    1877 

Germany 1873  Finland 1877 

France    1873  Greece    1878 

Italy    1873  Russia 1879 

Chile   1875  Haiti  1882 

Sweden 1875  Belgium    1884 

Turkey   1875  Japan    1885 

Spain 1874 

At  the  Pan-American  Conference,  which  met  in  Washington 
in  1890,  the  unnecessary  number  and  variety  of  tonnage  taxes 
and  dues  were  recognized  and  the  discriminations  which  resulted, 
but  the  recommendations  of  the  Conference  were  based  upon  an 
insufficient  knowledge  of  the  difficulties  involved  in  the  tonnage 
question  and  were  inadequate  and  impracticable.  At  a  meeting 
of  the  International  Institute  of  Statistics  in  Paris,  1889,  the  di- 
versity in  the  unit  of  measuring  vessels,  shipbuilding,  and  com- 
merce was  fully  described,  and  resolutions  urging  an  international 
tonnage  were  adopted,  but  without  result. 

Up  to  the  present  time,  therefore,  two  steps  have  been  taken 
toward  international  uniformity,  (i)  the  adoption  of  the  Moor- 
som ton  and  Moorsom  system  of  measurement,  and  (2)  the  in- 
ternational recognition  of  tonnage  certificates.  Regardless  of  the 
system  of  measurement  adopted,  however,  no  uniformity  will 


228  MERCHANT  VESSELS 

exist  until  the  method  of  treatment  of  the  various  spaces  is  iden- 
tical, and,  although  the  importance  of  the  subject  has  increased 
with  the  growing  international  navigation  and  commerce,  diver- 
sity still  prevails.  The  formulation  of  the  Panama  Canal  rules  in 
1913  offered  another  opportunity  to  adopt  a  common  system  which 
was  not  taken  advantage  of. 

The  benefits  of  an  international  system,  which  have  probably 
been  already  indirectly  indicated,  may  be  summarized  as  follows : 

1.  Statistics  of  navigation  and  commerce  would  be   simpler, 
more  intelligible  and  more  accurate. 

2.  A  shipowner  or  operator  would  understand  the  size  of  the 
vessels  he  employed  or  purchased. 

3.  The  annoyance  and  expense  of   remeasurement  would  be 
eliminated. 

4.  Taxation  would  be  less  involved  and  more  equitable. 

REFERENCES 

1.  JOHNSON,  E.  R. :     "Report  to  Secretary  of  War  on  Panama  Canal 

Traffic  and  Tolls."  Washington,  1913.  Chaps.  IV,  V,  VIII, 
IX,  XII  and  XIII  and  Appendices  VIII,  IX  and  XI.  (Com- 
parison of  English,  German,  United  States,  Suez,  and  Panama 
rules.) 

2.  HERNER,    HEINRICH:     "  Hafenabgaben    und    Schiffvermessung." 

G.  Fisher,  Jena,  1912.  Part  II.  (Comparison  of  German  and 
Suez  rules.) 

3.  WHITE,  W.  H. :    Manual  of  Naval  Architecture.     Murray,  Lon- 

don, 1894.  Chap.  II.  (Comparison  of  English  and  Suez 
rules.) 

4.  BERET,  V. :     "  Etude  sur  le  Jaugeage."     Societe  anonyme  de  pub- 

lications periodiques,  Paris,  1905.  (Comparison  of  English, 
French,  German,  and  Suez  rules.) 

5.  WALTON,  THOMAS:    Know  Your  Own  Ship.    Griffin  &  Co.,  Lon- 

don, 1917.  Chap.  VIII.  (Comparison  of  British,  Suez,  and 
Panama  rules.) 

6.  JOHNSON,   E.   R. :     "Report   to   Secretary   of   War   on   Panama 

Canal  Traffic  and  Tolls."  Washington,  1913.  Chap.  XII. 
(On  international  uniformity  in  tonnage.) 

7.  BERET,  V.:     "Etude  sur  le  Jaugeage."     Paris,  1905.     Pp.  21-30. 

(On  international  tonnage.) 
See  also  references  at  close  of  Chapter  XL 


CHAPTER  XIII 
THE  MEASUREMENT  OF  SAFETY 

The  three  elements  of  safety  in  ocean  transportation  are  ef- 
ficient seamanship,  proper  loading,  and  adequate  construction. 
The  first  is  not  pertinent  to  this  volume  ;  thel>econd  was  considered 
in  the  section  dealing  with  freeboard ;  leaving  the  third  for  dis- 
cussion here.  Methods  of  gauging  the  safety  of  vessels  from  a 
consideration  of  their  structure  have  existed  since  the  inception 
of  ocean  transportation,  the  ancient  lender  on  bottomry  having 
exercised  his  judgment  on  this  problem,  but  at  the  present  time  or- 
ganized classification  societies  are  principally  relied  upon  for  this 
service,  the  results  of  their  efforts  being  evidenced  by  the  publica- 
tion of  a  register.  This  records  particulars  of  the  vessel  and,  by 
assignment  of  a  symbol,  "  registers  "  the  society's  opinion  of  it. 
We  will  first  examine  the  purposes  served  by  the  inspection  and 
classification  system  of  such  associations. 

PURPOSES  OF  CLASSIFICATION 

In  general,  the  inspection  of  a  vessel  to  determine  its  sea- 
worthy qualities  is  of  interest  to  all  persons  connected  with  ocean 
transportation.  Insurance  companies  and  underwriters  have  been, 
for  many  years,  accustomed  to  depend  upon  the  information  fur- 
nished to  guide  them  in  accepting  risks  and  fixing  rates.  Since 
they  have  not  the  opportunity  of  personally  inspecting  every  risk 
which  is  offered,  they  must  in  many  cases  rely  largely  upon  the 
particulars  of  the  vessels  made  available  by  the  "  register."  As 
one  underwriter  expressed  it  in  his  testimony  before  a  Congres- 
sional investigating  committee,  "  the  average  underwriter  bases 
his  rates  primarily  on  his  experience  with  an  ownership,  a  trade, 
or  a  route,  but  for  individual  vessels  he  must  know  the  physical 
character  of  the  vessel,"  and  often  he  is  asked  to  write  insurance 
upon  a  vessel  which  is  in  a  far-off  port,  thus  forcing  him  to  resort 
to  such  printed  information  as  may  be  available. 

229 


230  MERCHANT  VESSELS 

The  second  group  of  interested  persons  consists  of  passengers, 
shippers,  and  consignees  whose  persons  and  goods  are  for  the 
time  being  entrusted  to  the  vessel.  In  the  complexity  of  present 
economic  life  the  inspection  and  classification  of  vessels  aids  them 
in  an  indirect  way,  for  a  shipper  or  consignee,  instead  of  keeping 
a  close  watch  upon  the  condition  of  a  vessel  through  the  published 
results  of  the  classification  societies,  is  much  more  likely  to  have 
his  attention  directed  to  any  unsatisfactory  condition  by  an  in- 
crease in  the  rates  charged  to  insure  the  cargo.  The  passenger 
receives  these  benefits  in  an  even  more  indirect  manner  since  the 
defects  of  the  vessel  increase  the  insurance  premium  on  the  hull 
and  this  places  the  operator  of  the  vessel  at  a  competitive  disad- 
vantage. However  devious  the  course  pursued,  it  cannot  be  de- 
nied that  these  benefits  ultimately  accrue  to  persons  in  this  category. 

More  direct  are  the  benefits  received  by  those  who  hire  vessels. 
The  register  furnishes  an  approximate  guide  in  the  selection  of  a 
vessel  which  is  suited  to  their  needs,  and  protects  them  against 
contracting  for  the  charter  of  a  vessel  notoriously  unsafe,  for 
which  they  might  find  it  difficult  to  secure  a  crew  or  insurance, 
and  to  which  they  would  be  reluctant  to  entrust  their  goods. 

The  public  authorities  are  also  in  a  position  to  receive  the  bene- 
fits of  these  services,  although  this  has  not  been  fully  taken 
advantage  of  in  the  United  States.  In  England  the  organization 
and  machinery  of  the  classification  society  has  been  utilized  to 
make  inspections  required  by  law,  so  that,  as  described  in  a  pre- 
vious chapter,  an  official  load  line  may  be  fixed  by  recognized 
societies.  The  work  of  such  societies  is  also  accepted  in  many 
cases  where  some  standard  is  necessary  for  legislative  purposes. 

It  is  weighty  evidence  of  the  value  of  this  work  that  vessel 
owners  in  practice  are  forced  to  avail  themselves  of  the  facilities 
afforded  by  these  societies.  It  is  not  compulsory  for  a  vessel 
owner  to  have  his  vessel  "  classed  "  by  a  society,  but  the  lack  of 
classification  makes  it  difficult  to  charter  or  insure  it.  A  vessel 
built  without  the  supervision  of  the  societies'  inspectors  may  sub- 
sequently receive  a  class  upon  request,  but  the  time  of  building 
furnishes  a  favorable  opportunity  to  have  a  survey  made  without 
loss  of  time.  As  expressed  in  the  report  of  the  Commissioner  of 
Corporations  on  Water  Transportation,  "  the  opinion  expressed 
by  a  body  of  experts  possessing  the  amplest  means  of  ascertaining 
the  condition  of  a  ship  and  enjoying  in  the  highest  degree  the  con- 


THE  MEASUREMENT  OF  SAFETY  231 

fidence  of  all  persons  engaged  in  shipping  is  therefore  regarded  as 
the  best  and  most  desirable  evidence  of  the  true  state  of  the 
vessel,  so  that  shipowners,  generally  speaking,  submit  to  the  con- 
ditions imposed  by  the  committees  of  classification  or  organiza- 
tions corresponding  thereto  in  order  to  obtain  their  testimonials." 
So  that  at  the  present  time  no  large  vessel  sails  without 'a  classi- 
fication certificate. 

From  the  objective  standpoint  the  work  of  the  classification 
societies  may  be  summarized  as : 

1.  The  inspection  and  classification  of  vessels  and  the  pub- 
lication of  the  results  in  a  form  facilitating  reference. 

2.  The  accumulation  of  a  code  of  rules  as  a  guide  in  vessel- 
construction,  designed  to  make  a  vessel  approximately  fit  for  the 
trade  intended. 

In  satisfactorily  ascertaining  the  safety  of  a  vessel  three  divisions 
appear.  In  the  first  place,  the  fitness  of  the  vessel  for  its  pur- 
pose may  be  approximately  gauged  by  mathematical  principles 
similar  to  those  employed  in  estimating  the  necessary  strength  for 
other  structures.  The  vessel  is  tested  like  a  girder,  a  bridge, 
or  a  foundation.  These  mathematical  calculations  must  secondly 
be  supplemented  by  a  considerable  amount  of  experience,  inas- 
much as  the  actual  stresses  and  strains  encountered  by  vessels 
under  many  varying  conditions  do  not  exactly  correspond  to  those 
ascertained  by  calculation.  This  experience  in  its  highest  state 
of  completeness  and  uniformity  can  be  supplied  only  by  some- 
body who  is  constantly  and  continuously  interested  in  the  subject. 
Thirdly,  some  public  or  semipublic  institution  is  a  prerequisite 
for  the  inspiration  of  confidence  and  insurance  of  uniformity; 
very  little  confidence  would  be  engendered  by  the  certificate  of 
an  unknown  surveyor,  no  progress  would  be  made  if  a  multitude 
of  different  rules  on  different  bases  were  simultaneously  in  use. 
For  these  reasons  classification  societies  have  come  to  occupy 
an  important  place  in  the  shipping  world,  and  we  may  briefly  ex- 
amine their  development  in  England. 

DEVELOPMENT  OF  CLASSIFICATION  SOCIETIES 

Although  in  early  days  it  might  be  possible  to  inspect  a  vessel 
every  time  it  was  offered  for  insurance  or  for  hire,  the  repetition 


232  MERCHANT  VESSELS 

of  inspections  became  exceedingly  burdensome  when  tonnage  in- 
creased. The  early  underwriters  accordingly  kept  lists  of  ships 
for  their  own  guidance  in  insuring,  and  it  was  only  natural  that 
such  private  papers  should  in  course  of  time  pass  from  hand  to 
hand.  They  were  probably  first  put  into  print  in  England  about 
1726,  but  no  copies  of  these  early  lists  now  exist.  The  oldest  copy 
of  a  Register  of  Shipping  now  extant  bears  the  date  1764-1766. 
It  shows  the  former  and  present  names  of  the  vessel,  the  owner 
and  master,  its  customary  trade,  tonnage,  number  of  guns  car- 
ried, the  port  and  year  of  construction,  and  the  classification  given 
it.  The  letters  A,  E,  I,  O,  and  U,  indicated  the  classification  of 
the  vessel,  and  the  letters  G,  M,  and  B  the  character  of  the  equip- 
ment. A  register  of  1768-1769  was  improved  by  references  to 
the  vessel's  rig  and  information  regarding  repairs.  The  letters 
a,  b,  c  now  designated  the  vessel  classification  and  the  numerals 
i,  2,  3,  the  condition  of  the  equipment,  a  combination  of  these 
being  the  origin  of  the  familiar  expression  of  praise  "  A  i." 

The  registry  of  shipping  up  to  this  point  was  probably  con- 
trolled and  operated  solely  for  the  benefit  of  the  insurance  fra- 
ternity. In  1797  a  new  system  of  classification  was  introduced 
which  based  the  rating  entirely  upon  the  place  of  build  and  the 
age  of  the  vessel,  and  thus  London-built  vessels  received  a  great 
advantage.  Accordingly,  in  1799  dissatisfied  shipowners  started 
the  New  Registry  of  Shipping.  The  Underwriters'  Register  (or 
Lloyd's  Register  as  it  was  called  after  1829)  was  known  as  the 
Green  Book  and  the  shipowners'  register  as  the  Red  Book.  These 
vessel  registers  were  competitors  for  38  years,  but  in  1837  were 
amalgamated  and  the  Society  of  Lloyd's  Register  assumed  prac- 
tically the  form  it  has  to-day.  This  is  a  voluntary  association 
of  those  interested  in  shipping,  who  support  the  activities  of  in- 
spection and  classification  by  subscription  to  the  product.  Up  to 
1837  it  was  a  body  closely  allied  with,  and  probably  controlled  by, 
the  Lloyd's  underwriters.  After  1837  it  acquired  a  fair  repre- 
sentation of  shipowners.  From  the  time  of  the  amalgamation 
the  second  function  we  have  mentioned,  that  of  prescribing  rules 
for  construction,  began  to  be  exercised.  It  would  serve  no  pur- 
pose here  to  trace  the  fight  of  representatives  of  the  outports  for 
greater  recognition,  the  gradually  increasing  minuteness  in  the  rules 
for  construction,  the  promulgation  of  rules  for  iron  ships  in  1855, 


THE  MEASUREMENT  OF  SAFETY  233 

the  institution  of  periodical  surveys  of  vessels,  the  adoption  of  the 
principle  in  1870  that  the  dimensions  of  the  vessels  and  not  their 
tonnage  should  govern  the  size  of  scantlings,  the  provisions  made 
for  the  survey  of  ships  abroad,  and  the  introduction  of  machinery 
surveys.  As  a  result  of  the  efficiency  of  its  work  and  the  large 
number  of  vessels  of  Great  Britain  on  the  seas,  Lloyd's  Register 
came  to  occupy  the  highest  position  in  the  shipping  world  as  an 
authority  upon  vessels. 

PROCESS  OF  REGISTRATION 

The  registration  procedure  is  practically  identical  in  all  societies. 
When  the  plans  for  the  construction  of  a  vessel  are  drawn,  they 
are  submitted  to  the  headquarters  of  the  registration  society.  The 
primary  cause  of  the  establishment  of  the  American  Bureau  of 
Shipping  was  the  refusal  of  Lloyd's  to  allow  plans  to  be  passed 
upon  in  the  United  States,  although  the  opinion  was  expressed 
that  plans  were  rinding  their  way  to  London  which  American 
interests  would  prefer  to  keep  at  home.  If  the  submitted  plans 
are  approved  the  work  of  construction  commences,  but  additional 
explanation  may  be  requested  or  modifications  suggested,  and  this 
usually  results  in  some  negotiations  before  approval.  The  mate- 
rial put  into  the  vessel  is  manufactured  under  survey  and  sub- 
jected to  the  tests  required  by  the  rules,  and  the  various  fittings 
must  also  receive  the  approval  of  the  surveyors.  The  case  of  the 
Quistconck,  built  at  Hog  Island,  the  equipment  of  which  failed  to 
receive  a  Lloyd's  rating  because  of  a  defective  anchor  chain,  may 
be  recollected.  The  vessel  might  be  said  to  be  built  under  the 
eye  and  control  of  the  surveyors.  Upon  completion,  a  classifi- 
cation is  assigned.  A  vessel  may  be  offered  after  completion 
for  examination  and  registration,  but  this  process  is  not  very 
satisfactory.  This  oversight  is  maintained  for  twelve  years  after 
launching,  a  periodical  survey  being  conducted  every  four  years. 
In  case  of  an  accident  necessitating  repairs  between  these  periods, 
the  repairs  are  similarly  supervised.  The  boilers  are  subject  to 
inspection  at  least  once  a  year,  after  six  years.  In  order  to  main- 
tain her  class,  the  vessel  must  pass  these  surveys,  but  naturally 
some  vessels  drop  from  the  very  highest  to  a  lower  class  during 
the  period  by  reason  of  deterioration. 


234  MERCHANT  VESSELS 

DESCRIPTION  OF  LLOYD'S  REGISTER 

On  the  following  page  a  reproduction  is  given  of  a  page  from 
a  recent  Lloyd's  Register.  We  might  take  the  steamer  Glengyle 
for  purposes  of  explanation.  In  the  first  column  appear  the  num- 
ber of  the  vessel  in  the  register,  her  official  number,  and  the  code 
letters  assigned  for  identification  purposes.  In  the  second  column 
appear  the  name  of  the  vessel  and  its  former  name  if  a  change  has 
occured.  Thus  the  steamer  Glenford,  on  the  same  page,  was 
formerly  the  Christina.  Tables  elsewhere  facilitate  the  tracing 
of  vessels  through  changes  in  name.  In  bold  type  the  Glengyle 
is  described  as  a  steel  twin-screw  steamer.  The  master  from 
1884  to  1914  was  R.  Webster,  and  the  vessel  is  fitted  with  three 
steel  decks,  electric  light,  refrigerating  machinery,  and  wireless. 
In  column  4  are  shown  the  gross  tonnage,  underdeck  tonnage, 
and  net  tonnage.  Columns  5,  6,  and  7  give  the  particulars  of 
classification.  This  vessel  is  marked  >J«iooAi.  The  black  cross 
signifies  that  the  vessel  was  constructed  under  special  survey. 
The  designation  looA  means  that  an  iron  or  steel  vessel  was  built 
according  to  the  rules  in  force  since  1869,  of  the  highest  quality. 
As  the  vessel  becomes  poorer,  its  rating  is  changed  to  95A,  QoA, 
85 A,  8oA,  and  75 A.  Vessels  marked  simply  Ai  are  of  iron  or 
steel  but  constructed  for  a  special  purpose.  Iron  vessels  built 
according  to  the  rules  in  force  between  1864  and  1871  are  classed 
as  /A  »  /§\  >  °r  /€\  »  and  wooden  or  composite  vessels  are  marked 
A  in  red  or  A  in  black,  or  JE.  The  mark  *  indicates  iron 
vessels  built  with  thicker  plating  than  required  for  /&  •  The 
figure  i  following  rooA  indicates  that  the  vessel's  equipment  has 
been  sanctioned ;  the  mark  -,  that  the  equipment  is  deficient  com- 
pared with  the  rules.  The  date  shows  that  the  last  survey  was 
made  in  October,  1914.  and  the  port  of  survey  is  given  as 
Newcastle.  The  machinery  is  marked  with  letters  to  indicate  its 
classification,  the  significance  of  letters  being  found  by  reference 
to  tables  in  the  rules.  In  red  letters  it  is  indicated  that  the 
machinery  and  boilers  and  refrigerating  machinery  received  a 
Lloyd's  certificate  by  special  survey  while  building,  in  October, 
1914.  Column  7  shows  the  date  when  the  tail  shaft  was  last 
seen,  in  this  case  while  building.  From  columns  8  and  9  we 
find  that  this  vessel  was  constructed  in  1914,  by  Hawthorne, 
Leslie  &  Company,  at  Newcastle,  and  that  its  anchors  and  chains 


Jljg  II       ill 


PN  -««       fi 


&      lSS£ 


3     &jfl 


I  HI  *  j  in  41*111  lugf  j*i    I,  s 

sLg^yi^IillIfelllllLlillil^llI  rf|!  s 

Sfl^f  ,5«!|^-«3f  SlllJ<3|E38ll5^Il2l5t'*.1J     feHj       £ 


^•J^-^SiHi^ 


I'll  I 


(NO  OO  •*»•   o       •»     O 

oo  a        o       —  a    §>  •— i 

00  —  00  0>0        ~      C5 


"«~0~ 

fel 


236  MERCHANT  VESSELS 

were  proved  at  a  machine  under  the  superintendence  of  Lloyd's 
Register  (Lloyd's  A  &  CP).  The  letters  A  &  CP  would  have 
indicated  merely  a  machine  recognized  by  Lloyd's  Register.  Col- 
umn 10  gives  the  owner's  name  —  the  Glen  Line,  McGregor, 
Gow  &  Company,  Ltd.  Column  1 1  shows  the  length  as  500.2  feet, 
the  breadth  62.3  feet,  and  the  depth  34.7  feet,  the  deck  erections 
consisting  of  a  poop  60  feet  long,  a  bridge  of  192  feet,  and  a 
forecastle  of  88  feet.  We  find  also  from  column  n  that  this 
vessel  has  water-ballast  arrangements  (WB),  a  cellular  double 
bottom  (Cell  DB),  a  flat  keel  and  bar  keel  2.l/2  inches  in  depth 
(FK  &  BK),  8  cemented  bulkheads  (8  B  H  Cem),  a  deep 
tank  33  feet  long  with  1170  tons  capacity  (DTa  33  feet  H7ot), 
a,  fore  peak  tank  of  174  tons  (FPT  I74t),  and  an  after  peak 
tank  of  49  tons  (APT  49t).  Column  12  shows  that  the  vessel 
is  British  and  is  registered  at  London.  Column  13  gives  the 
particulars  regarding  the  engine,  this  vessel  having  triple-expan- 
sion engines  with  6  cylinders,  their  dimensions  and  stroke  being 
given,  a  boiler  pressure  of  200  pounds  to  the  square  inch,  a  nom- 
inal horse  power  of  998,  5  single-ended  boilers,  20  corrugated  fur- 
naces, 380  square  feet  of  grate  surface,  14,775  square  feet  of  heat- 
ing surface,  using  forced  draft.  The  engine  maker's  name  is  also 
given.  Column  14  shows  the  molded  depth  37  feet,  6  inches ;  the 
freeboard  amidships  8  feet,  5  inches ;  and  the  corresponding  draft, 
29  feet,  7  inches.  The  last  column  shows  the  registers  in  which 
the  vessel  is  classed  if  other  than  Lloyd's  and  the  date  of  the 
vessel's  Board  of  Trade  certificate.  This  gives  an  idea  of  the 
information  conveyed  by  the  Register  about  a  vessel,  surely  a  very 
considerable  amount  to  be  included  in  a  space  of  less  than  4^/2 
square  inches,  as  in  this  case.  There  remains  to  be  explained 
only  the  basis  for  that  very  important  feature  in  the  digest,  the 
classification  or  rating,  in  this  case  looAi.  The  classification 
rules  which  form  this  basis  are  considered  in  subsequent  sections. 

OTHER  IMPORTANT  REGISTERS 

Classification  societies  similar  to  Lloyd's  have  been  established 
in  all  the  important  maritime  countries,  but  with  the  exception 
of  France  have  never  attained  similar  importance,  for  reasons 
previously  mentioned.  There  are  the  British  Corporation  in 
Great  Britain,  the  Bureau  Veritas  of  France,  the  Germanischer 


THE  MEASUREMENT  OF  SAFETY  237 

Lloyd  of  Germany,  the  Veritas  Austro-Ungarico  of  Austria,  the 
Nederlandische  Wereinigung  of  Holland,  the  Norske  Veritas  in 
Norway,  the  Registro  Nazionale  Italiano  in  Italy,  and  the  Veritas 
Hellene  in  Greece.  Of  these  the  American  Bureau  of  Shipping 
is  the  most  important. 

American  Bureau  of  Shipping. —  This  was  incorporated  in 
New  York  in  1862  as  the  American  Shipmasters'  Association, 
and  its  name  was  changed  to  the  present  title  in  1898.  It  was 
organized  to  collect  and  disseminate  shipping  information,  ascer- 
tain and  certify  the  qualifications  of  masters  and  promote  safety 
at  sea.  In  1867  there  was  established  the  Record  of  American 
and  Foreign  Shipping,  a  shipping  register,  and  in  1882  the 
American  Lloyd's  Register  was  purchased  and  combined  with  this 
Bureau,  giving  the  right  to  use  the  name  American  Lloyd's.  In 
1908  it  absorbed  the  United  States  Shipowners',  Shipbuilders', 
and  Underwriters'  Association.  It  has  eight  officers,  a  board 
of  managers  composed  of  the  insurance,  ship  building,  ship- 
operating,  repairing,  and  scientific  representatives,  an  executive 
committee,  finance  and  audit  committee,  and  a  classification  com- 
mittee composed  of  four  shipbuilders,  four  vessel-owners  and 
operators  and  one  insurance  man.  There  is  a  membership  limited 
to  100  and  composed  of  persons  interested  in  shipping,  who  pay 
no  fees,  the  income  for  the  support  of  the  organization  being  de- 
rived from  the  fees  charged  for  making  surveys.  There  is  also 
necessary  a  corps  of  surveyors  in  the  United  States  and  abroad, 
some  doing  work  exclusively  for  the  American  Bureau  and  others 
being  nonexclusive  surveyors.  The  corporation  issues  no  stock 
and  pays  no  dividends,  being  a  purely  mutual  cooperative  organi- 
zation for  rendering  a  necessary  service  in  shipping  and  insurance 
circles.  This  organization  maintained  a  more  or  less  precarious 
existence  for  a  number  of  years  being:,  as  one  of  its  officers  ex- 
pressed it,  "the  child  of  one  insurance  company  —  the  Atlantic 
Mutual."  During  this  period  (1916)  it  absorbed  the  Great  Lakes 
Register,  a  society  for  classing  vessels  on  the  Great  Lakes.  Three 
attempts  were  made  in  1913  and  1915  by  the  American  Bureau  to 
amalgamate  with  British  Lloyd's,  but  without  success.  The  latter 
attempt  furnished  the  opportunity  for  starting  a  strong  American 
Register.  It  was  thought  that  it  would  be  possible  to  have  vessel 
plans  passed  upon  by  the  American  committee  without  reference 
to  London,  and  the  question  was  put  to  Lloyd's  Register  in  this 


238  MERCHANT  VESSELS 

form :  Suppose  an  American  naval  architect  designs  a  new  ship 
and  your  American  committee,  formed  under  this  coalition,  pa^ed 
the  plans  for  that  ship,  will  Lloyd's,  in  London,  accept  the  de- 
cision of  the  American  committee  or  will  the  plans  have  to  go  to 
London?  The  secretary  of  Lloyd's  responded  that  the  plans 
would  have  to  go  to  London,  all  the  plans  would  have  to  go  to 
London.  Whereupon  the  reorganization  committee  decided  to 
reorganize  its  own  classification  society.  This  society  received 
the  hearty  support  of  the  United  States  Board  during  the  World 
War.  The  number  of  exclusive  surveyors  greatly  increased,  and 
while  in  1916  it  was  classing  8  per  cent  of  American  vessels,  in 
1919,  due  largely  to  the  business  distributed  to  it  by  the  Shipping 
Board,  it  was  classing  68  per  cent  of  American  vessels.1  Its  im- 
portance to  an  American  merchant  marine  can  hardly  be  over- 
estimated. 

Description  of  the  American  Register. —  Below  is  given  a  sam- 
ple page  of  the  Record  of  American  and  Foreign  Shipping,  the  most 
prominent  American  register.  For  purposes  of  explanation  we 
will  use  the  steamer  Lake  Ledan.  The  first  column  shows  the 
register  number,  official  number,  and  signal  letters  of  the  vessel, 
being  followed  by  the  name  of  the  vessel,  prefixed  by  a  Maltese 
cross,  indicating  that  the  vessel  was  built  or  repaired  under  in- 
spection. If  the  name  of  the  vessel  has  been  changed  the  former 
name  is  also  given,  as  in  the  case  of  the  Lake  Linden,  formerly 
the  War  Cloud.  In  the  second  column  the  vessel  is  described  as 
a  one-deck  (iD)  bulk  carrier,  built  of  steel  with  4  water-tight 
bulkheads  (4  BH),  with  submarine  signals  and  water-ballast 
tank  (W.  Bal.).  Column  3  indicates  that  it  is  a  screw  steamer, 
and  its  nationality  is  given  as  American  in  column  4.  Column 
5  shows  its  hailing  port  as  Superior,  Wisconsin.  In  columns  4 
and  5  combined  its  length  is  given  as  251  feet,  its  breadth  as  43.7. 
its  depth  as  22.2  feet,  and  its  molded  depth  as  24  feet  2^2  inches. 
It  has  a  poop  extending  for  25  feet,  a  bridge  64  feet  long,  and  a 
forecastle  23  feet  in  length.  Column  6  furnishes  the  net  tonnage 
(1432),  the  gross  tonnage  (2369),  and  the  dead-weight  tonnage 
(3525).  In  column  7  it  is  stated  that  the  freeboard  allowance  is 
3  feet  4  inches  at  a  draft  of  21  feet.  Columns  8  and  9  show  that 
it  was  built  in  June,  1918,  by  the  Superior  Shipbuilding  Company 

1  Testimony  of  S.  Taylor  before  Subcommittee  on  the  Merchant  Marine 
and  Fisheries,  July  16,  1919.    "Hearings  on  Marine  Insurance." 


a 


o    5 

III, 
sill 

ill! 

Ills' 


o       •=;« 


Ill 

sgl 

£?6 

ssa 


sgi 

ill 


£1 

-i 

w 


|! 
«i 


. 


il 


II 


41 


e 


II 


I15! 


Jli 


Clevela 

43.7  |  22. 
B6V  F20' 


Wyand't 

43.8  |  22.2 


1! 


Mamtow 

43.7  |  20.4 
B04-  F26' 


5"     O 

!  ^ 

M 


I 


3 


ils 

': 

il 


in 

i  ^ 


23 


239 


3 

li 


24o  MERCHANT  VESSELS 

at  Superior,  Wisconsin.  It  is  owned  by  the  United  States  Ship- 
ping Board  (Col.  10).  Column  n  gives  the  details  of  the  engines 
and  boilers  and  indications  of  special  features.  This  vessel  has 
engines  of  3  cylinders  (3  Cyl)  of  the  triple-expansion  type  (TE), 
the  dimensions  of  the  cylinders  being  given,  2  single-ended  Scotch 
boilers  (2  SB),  the  dimensions  of  which  are  also  given,  a  grate 
surface  of  114  square  feet  (114  GS),  a  heating  surface  of  5466 
square  feet  (5466  HS),  a  working  pressure  of  180  pounds  to 
the  square  inch  (WP  180  Ibs.)  The  engines  have  an  indicated 
horse  power  of  1250  (1250  IHP),  and  a  certificate  has  been 
granted  for  the  electrical  apparatus.  The  vessel  was  docked 
for  small  repairs  in  January,  1919.  Column  12  shows  that  this 
vessel  received  the  highest  classification,  »^A  i  ©  ,  as  is  true 
of  all  other  vessels  on  this  page,  except  those  for  which,  no 
mark  appears  in  this  column,  which  are  not  classified  by  the 
American  Register.  If  of  construction  less  adequate  for  its  pur- 
poses this  vessel  would  have  been  marked  A  il/2  or  A  2.  Some 
vessels  are  indicated  as  being  classed  only  for  particular  trades. 
The  ©  applies  to  the  equipment.  The  mark  *J«A.M.S.  signi- 
fies the  highest  classification  of  the  American  Bureau  of  Shipping 
and  special  survey  during  construction  for  machinery  and  boilers. 
Where  the  equipment  is  not  in  compliance  with  the  requirements 
of  the  rules  a  dash  is  substituted  for  the  mark  ©  .  In  the  final 
column  it  is  seen  that  this  vessel  is  not  classified  with  other  classi- 
fication societies,  but  we  find  other  vessels  on  the  same  page 
classed  in  the  British  Lloyd's  (BL). 

LLOYD'S  RULES  AND  TABLES  FOR  CLASSIFICATION 

The  construction  of  the  vessel  is  largely  regulated  by  the  size 
of  the  scantlings  required.  Until  1870  it  was  the  custom  to  pre- 
scribe such  size  in  proportion  to  the  under-deck  tonnage  but  the 
tonnage  of  a  vessel  is  rather  uncertain  until  completed  and  takes 
no  account  of  dimensions.  Consequently,  a  double  system  of 
numerals  was  adopted,  one  numeral  being  assigned  to  the  trans- 
verse parts  and  one  to  longitudinal  parts.  This  is  simply  a  con- 
venient method  of  taking  into  consideration  the  dimensions  of  the 
vessel.  The  transverse  or  framing  numeral  is  arrived  at  by  the 
addition  of  the  vessel's  molded  depth  and  breadth.  These 
numerals  are  tabulated  for  vessels  of  increasing  size  and  under 


THE  MEASUREMENT  OF  SAFETY 


241 


each  numeral  are  given  the  scantlings  and  spacings  of  transversely 
disposed  parts  required  for  a  vessel  of  such  dimensions.  The 
longitudinal  or  plating  numeral  is  the  product  of  the  transverse 
numeral  multiplied  by  the  length  of  the  vessel.  These  numerals 
are  likewise  tabulated  and  under  each  is  given  the  sizes  for 
longitudinal  parts,  shell  plating,  keel,  decks,  stringers,  etc.  The 
following  table  from  Holms  gives  an  idea  of  the  resulting 
numerals : 


Plating  number       Framing  number 


Approximate  dimensions 


B 


D 


2,500 

27.0 

95 

19-5 

7-5 

5,000 

35-5 

140 

24 

"•5 

10,000 

48.5 

208 

3i 

T7-5 

15,000 

58.0 

261 

36 

22 

20,000 

66.0 

305 

40-5 

25 

25,000 

73-o 

343 

44 

29 

30,000 

79-5 

378 

48 

31 

35,000 

85.0 

412 

5i 

34 

40,000 

91.0 

441 

54 

37 

45,000 

96.0 

468 

57 

39 

50,000 

100.5 

496 

59-5 

4i 

55,000 

105.0 

520 

62 

43 

60,000 

1  1  0.0 

545 

64-5 

45 

65,000 

II3-5 

568 

66.5 

47 

70,000 

1  1  8.0 

59i 

69 

49 

75,000 

I22.O 

612 

7i 

5i 

By  reference  to  the  approximate  numerals,  as  stated,  the  neces- 
sary requirements  for  the  vessel  may  be  ascertained.  By  ex- 
perience these  must  be  modified  and  adapted  for  vessels  of  various 
design  and  structure. 

It  must  not  be  supposed,  as  is  sometimes  done,  that  the  thickness 
of  the  shell  plating  or  other  scantlings  is  based,  in  the  first  instance, 
on  the  mere  magnitude  of  the  numerals;  for  instance,  the  bottom 
plating  of  a  vessel  whose  second  numeral  is  20,000  is  not  twice  as 
thick  as  it  is  in  one  having  a  numeral  of  10.000.  There  is  no  fixed 
relation ;  in  the  former  it  is  .54  inch,  in  the  latter  .44  inch.  The 
scantlings  appropriate  to  various  sizes  and  types  of  vessels  were 
decided  in  the  beginning  more  or  less  tentatively  or  empirically,  and, 
in  the  course  of  time,  as  dictated  by  experience,  they  were  suitably 
modified.  The  numerals  may  be  regarded  merely  as  a  means  of  iden- 
tification, to  indicate,  as  it  were,  the  general  size  of  the  vessel,  and 
what  scantlings  are  in  her  case  appropriate.  If  all  vessels,  though 
varying  in  size,  were  of  identical  proportions  and  form,  it  would  be 


242  MERCHANT  VESSELS 

a  matter  of  indifference  what  the  numerals  were;  a  single  dimension, 
the  length,  breadth,  or  depth,  or  the  volume,  or  the  tonnage  would 
serve  equally  well  as  a  means  of  proclaiming  the  size  and  what  scant- 
lings would  be  most  appropriate.  But  vessels  vary  greatly  in  form, 
and  it  is  therefore  difficult  to  devise  numerals  which,  while  simple  in 
application,  will  form  in  all  cases  a  theoretically  correct  basis.2 

In  other  societies  other  methods  are  followed,  the  British  Cor- 
poration, for  example,  setting  out  the  requirements  under  the 
length,  breadth,  depth  and  combinations  thereof. 


AMERICAN  BUREAU  OF  SHIPPING  RULES  FOR  CONSTRUCTION 

It  is,  of  course,  impossible  to  show  the  many  different  elements 
which  enter  into  the  requirements  for  vessel-building  in  order 
to  meet  the  requirements  of  classification.  All  that  can  be  done  is 
to  take  a  few  items  from  the  book  of  rules  with  the  object  of 
showing  the  value  of  this  system  of  supervision  and  the  thorough- 
ness with  which  the  survey  is  attempted. 

i.  Keels,  Stems,  and  Stern  Frames. —  The  dimensions  of  these 
parts  are  principally  governed  by  the  length  of  the  vessel  as 
measured  from  the  stem  to  the  after  side  of  the  rudder  post  along 
the  summer  freeboard  line.  The  requirements  are  tabulated  in  a 
form  similar  to  that  given  below. 


L 

KEEL    PLATE                                         CENTER   GIRDER 

Thickness                                    Thickness 

Breadth    Amidships     Ends    Amidships    Ends     Boiler  space 

IOO 

125 
150 

39 
40 
40 

.40 
-44 
•50 

OJ  OJ  OJ 

COON  Ki 

.28 

•30 
•32 

•24 

.26 

.28 

3 

.40 

2.  Frames.  The  dimensions  and  strength  of  frames  is  in  ac- 
cordance with  two  factors,  M  and  K.  The  factor  M  is  obtained 
by  considering  the  spacing  of  the  frames,  the  height  amidships, 
and  the  distance  from  the  summer  load  line  to  one-half  the  height. 
The  factor  K  is  obtained  by  considering  the  spacing  of  the  frames, 
the  distances  from  the  lowest  tier  of  beams  to  a  designated  dis- 
tance above  the  freeboard  deck  and  a  percentage  of  the  breadth 

2  Holms.  Practical  Shipbuilding,  Longmans,  Green  &  Co.,  London,  1916, 
P.  47- 


THE  MEASUREMENT  OF  SAFETY 


243 


varying  from  one-half  to  one-quarter.  A  tabulation  of  the  dimen- 
sions required  then  enables  one  to  find  the  demands  for  any  com- 
bination of  values  for  M  and  K,  as  is  shown  by  the  following 
sample  of  a  table : 

CHANNEL  FRAMES 


Values  of  M 


K 

42 

46 

50 

o 

2 

4 
6 

9x3     x  .42  x  .44 
9  x  $y2  x  .38  x  .50 
9  x  3^  x  .38  x  .50 
9x3Vix.38x.50 

9x3^  x\38  x  .50 
9x3^x.38x.so 
9  x  V/2  x  .42  x  .50 
9  x  $y2  x  .44  x  .55 

etc. 
etc. 
etc. 
etc. 

3.  Beams.  The  requirements  for  beams  are  principally  depend- 
ent upon  the  length  and  the  value  of  a  factor  N,  the  latter  being 
derived  from  the  spacing  of  the  beams,  the  character  of  the  deck 
and  the  height  of  the  freeboard  and  other  decks.  The  following 
table  shows  the  derivation  of  the  dimensions: 

CHANNELS  FOR  BEAMS,  BULKHEAD  STIFFENERS,  ETC. 
Values  of  N 


L 

10 

12 

15 

JCC 

6  x  3  x  .42  x  .48 

etc. 

2° 
16.25 

17- 

6  x  3  x  .32  x  .44 
6  x  3  x  .42  x  .48 

7  x  3  x  .38  x  .48 
7  x  3  x  .38  x  .48 

etc. 
etc. 

4.  Shell  Plating.     This  is  dependent  upon  the  length  and  spac- 
ing of  frames  and  the  freeboard.     Fo-r  example: 


SPACING 

THICKNESS 

L 

Bottom  in 
single 
bottom 
vessels 

Sides 
bottom  in 
double 
bottom 
vessels 

Ends 

Fore- 
castle 

Poop 

IOO                 2 
105                 2 
110                 2 

i                 .32 
i                 .32 
i                 .32 

•30 
•30 
•32 

.26 
.26 
.26 

.22 
.22 
.24 

.22 
.22 
.24 

•5.  Decks.     The  requirements  for  decks  are  influenced  by  the 
length,  breadth,  and  freeboard  of  the  vessel. 


244  MERCHANT  VESSELS 

STRENGTH  DECK  AND  TOPSIDES  —  ONE  DECK 


"PR  PP 

LENGTH                                                 THICKNESS                       AREAS   FOR   BREADTHS  OF 
BOARD 

Topside 

Sheer          and            Dedc     I2       l6      2Q                2g 
strake     streamer 

plate 

6 

•30 

•30 

.18 

3 

4 

6 

7 

9 

IOO 

5 

•30 

•30 

.18 

3 

4 

6 

8 

TO 

4 

•30 

•30 

.18 

3 

5 

7 

Q 

10 

3 

•30 

•30     . 

.18 

3 

5 

7 

9 

II 

6.  Equipment.  Sails,  boats,  anchors,  chains,  hawsers,  com- 
passes, windlass,  anchor  cranes,  hawse  pipes,  steering  gears,  etc., 
are  all  covered  by  the  rules.  We  might  take  as  an  illustration 
anchors,  chains  and  hawsers,  which  are  governed  by  the  tonnage 
of  the  vessel,  ascertained  by  a  rough  calculation,  using  the  length, 
breadth,  depth  and  coefficient  of  fineness. 

Many  other  items,  such  as  rudders,  keelsons,  double  bottoms, 
stanchions,  pillars,  girders,  bulkheads,  ceiling,  riveting,  cement- 
ing, and  painting,  etc.,  are  considered  in  the  rules  but  the  fore- 
going is  sufficient  to  give  some  conception  of  the  method  by  which 
the  construction  of  vessels  is  regulated  and  the  adequacy  of  the 
construction,  material  and  equipment  tested.  This  method  differs 
little  in  fundamental  principle  from  that  of  Lloyd's ;  though  the 
arrangement  of  tables  and  statement  of  formulas  may  vary 
similar  factors  are  considered  in  arriving  at  results. 

The  Commissioner  of  Corporations,  in  a  report  in  1909,  gives 
the  following  Comparison  of  the  ratings  of  the  American  Bureau, 
Lloyd's  Register  and  the  Bureau  Veritas : 


American                            Lloyds                                Bureau 
Bureau                             Register                        .      Veritas 

A  i 
A  iV2 
A  1% 

A    2 

A  2y2 

A  3 

A  r 
A  i 
A  i  red 
A  i  'red 
AE  i 
AE  i 

3/3-1-1 

S/6-i.i 
5/6-2.1 
5/6-2.1 
3/4-2.1 
1/2-3.2 

THE  MEASUREMENT  OF  SAFETY  245 


REFERENCES 

1.  Commissioner  of  Corporations:     "Report  on  Transportation  by 

Water  in  the  United  States."  Washington,  1909.  Pp.  360- 
365.  (Description  of  American  classification  societies.) 

2.  KIRKALDY,  A.  W. :     British  Shipping.     Paul,  Trench,  Trubner  & 

Co.,  London,  1914.  Book  II,  Chap.  V.  (Description  of  his- 
tory and  operations  of  Society  of  Lloyd's  Register.) 

3.  Lloyd's  Register:     "Annals  of  Lloyd's  Register."     London,  1884. 

(History  of  Lloyd's  Register  and  system  of  classification.) 

4.  HOLMS,    C. :     Practical  Shipbuilding^.     Longmans,    Green   &   Co., 

London,  1916.  Chap  V.  (Brief  history  of  Lloyd's,  explana- 
tion of  Lloyd's  rules  and  brief  discussion  of  the  British  Cor- 
poration and  Germanischer  Lloyd's  rules.) 

5.  THEARLE,  S.  J.  P.:     "The  Classification  of  Merchant  Shipping," 

paper  before  Greenock  Philosophical  Society,  January  15,  1914. 
Lloyd's  Register  Printing  House,  London,  1914.  (The  value  of 
classification  and  classification  societies.) 

6.  Lloyd's  Register:     Rules  for  the  Classification  of  Vessels. 

7.  American  Bureau  of  Shipping:     Rules  for  Building  and  Classing 

Vessels.     1917. 

8.  Lloyd's  Register  of  Shipping.     Annually. 

9.  The    Record    of    American    and    Foreign    Shipping.     Annually. 

American  Bureau  of  Shipping,  New  York. 


INDEX 


Act    of    1876    relating    to    free-     Application  of  measurement  rules, 


board,   167 
Act  of    1890    relating    to    free- 
board,  167 

Actual  dead  weight,  163 
Actual  displacement,   158 
Advantages,  of  cantilever  vessel, 
87,  88 

—  of  electric  system  turbine,  114 

—  of  hydraulic  transformer,    115 

—  of     internal-combustion     en- 

gines,  128-131 

—  of    longitudinal    construction, 

40-41 

—  of  oil-burning    engines,    120- 

123 

—  of  private   industrial   carriers* 

58 

—  of  producer-gas  engine,  125 
—r  of     quadruple-expansion     en- 
gine,  I  TO 

—  of    raised-quarterdeck   vessel 

74 

—  of  steamers     compared     with 

sailing  vessels,   8-u 

—  of  steel    construction    of    ves 

sels,  25 

—  of  towing  unrigged  craft,  100 

—  of  transverse  construction,  40, 

-  of  turret-deck   vessel,   83,  84 

—  of  water-tube  boiler,  118 

—  of  well-deck   vessel,   78 
Affreightment,  contract  of,  60 
Alternatives   for   required   struc- 
tural strength,  39 

American    Bureau    of    Shipping 
history  of,  237-238 

—  rules    for    construction,    242- 

245 
American     Register,     description 

of,   238,   239 
American  tonnage  rules,  179-200 

—  defects  of,  191 


247 


to    between-deck    tonnage, 
-   185,  209-211 
— -  to  crew  space,  196,  215-224 

—  to  depths,  209 

—  to  length,  1 80,  208 

—  to  navigation  space,  198,  225 

—  to  propelling-power  space,  192, 

216 

—  to  space  above  tonnage  deck, 

i 88,  212-216 

—  to  space  below  tonnage  deck, 

187,  212 

—  to  superstructures,  212 

—  to  tonnage  deck,  179,  208 

—  to    tonnage-length     divisions, 

208,  209 

—  to  tonnage   under   tonnage 

deck,  209 

Area  of  transverse  sections,  meas- 
urement of,  181 

Arrangement  and  construction  of 
decks,  66 

Awning-deck  vessel,  construction 
of,  95»  96 

Bark,  definition  of,  4 
Barkentine,  definition  of,  4 
Beam,  length  and  draft,  ratio  be- 
tween, 52 

—  of  vessel,  3 

-  purpose  of,  36,  37 

-  rules  for  construction  of,  243 
Beam  engine,  103 

Beam  knees,  37 

Between-deck  tonnage,  measure- 
ment of,  185,  209-211 
Bilge,  description  of,  44 
Bilge  keelson,  38 
Bilge  strineer,  38 
Block   coefficient  of  fineness,   53 

-  variations  of,  53 

—  table  of,  169 


248 


INDEX 


Board    of    Trade,    recommenda 

tions  on  freeboard,  173 
Body  plan  of  vessel,  43 
Boiler,  cylindrical,  117 

—  marine,  117,  118 

—  water-tube,   117 

—  Yarrow,  description  of,  117 
Boiler  room,  44 

Bounties,  effect  of  on  sailing  ves- 
sels, 15 

Brig,  definition  of,  4 
Brigantine,  definition  of,  5 
British    table    of    freeboard    fac 

•tors,  168 
"Builders'      Old      Measurement' 

rules,  203 
Bulk  cargoes,  in  sailing  vessels, 

T3 
Bulk  system   for  oil,  advantages 

of,  90 

Bulkheads,  description  of,  37 
Bunkers,  coal,  44 
Buoyancy,  reserve,  54,   169 
Buoyancy  and  displacement,  157, 

158 

Calculation,  of  displacement,  159 

—  of  principal   volume,    184,   185 

—  of  tonnage  items,    197 
Camber,  definition  of,  44 
Canals,  as  a  handicap  to  sailing 

vessels,  n 

-  saving  in  distance  by,   II 
Cantilever  vessel,  advantages  of, 
.87,  88 

—  construction  of,  87,  88 
Capacities,    illustration    of    coal 

bunker,  156 

—  illustration  of  hold,   155 

—  illustration    of    water   ballast 

155 

Cargo,  kinds  of,   140,   153 
Cargo  boat,  essentials  of  a  good, 

69 
Cargo  liners,  definition  of,   57 

—  purpose  and  services  of,  57 
Cargo    space    tonnage    estimated 

from      register      tonnage, 

154 

Cargo  tonnage,  measurement  of, 

152 

Cargo  vessels,  principal  develop- 
ments in,  101 


—  principal  spaces  in,  45 
Carlings,  37 

Carriers,  industrial,  57 

Center  keelson,  38 

Certificate  of  tonnage,  copy  of, 
199 

Classification,  of  kinds  of  meas- 
urement tonnage,  137 

—  of  marine    engines,    104 

—  of   merchant   marine   accord- 

ing to  construction,  30,  31 
Classification    societies,    develop- 
ment of,  231-233 

—  work  of,  229-244 

—  of  vessels,  by  structural  fea- 

tures, 68-101 
-  purposes   of,   229-231 
Clipper  ship,  4 
Coal  bunkers.  44 

—  capacity  of,  156 

Coastwise    trade,    sailing   vessels 

in,  12 
Coefficients,     block,     illustration 

of,  54 

table  of,  169 

Coefficients  of  vessel  dimensions, 

Combination  reciprocating  and 
turbine  engines,  115 

Combination  vessels,  57 

Commission  of  1874  on  free- 
board, 167 

Comparison,  of  coal  and  oil- 
burning  vessels,  123 

—  of    gross    tonnage    and    dead 

weight,    153.    154 

—  of  line  and  tramp  services,  59 

—  o  ^registration  society  ratings, 

'244 

—  of       tonnage       measurement 

rules,  203-228 

—  of  types    of    vessels,    66-102, 

116 

Composite  vessel,  26,   51 
Concrete    vessel,    advantages    of, 

28,  29 

—  description  of,  27,  51 

—  obstacles    in    development   of, 

27,  28 

Condensers,  104 

Construction,  and  deck  arrange- 
ment of  merchant  vessels, 
66 


INDEX 


249 


Construction,  materials  of,  18-31 

—  of  composite  vessel,  26 

—  of  keels,  33 

—  of  spar-deck  vessel,  97,  98 

—  of  steam   schooner,   95 

—  of  transverse    frames,    34 

—  of  turret-deck  vessel,  82 

—  purposes   of   vessel,   48-50 

—  rules    for,    American    Bureau 

of  Shipping,  242,  245 

Contract  of  affreightment,  mean- 
ing of,  60 

Contracts,  line  and  tramp  ser- 
vices, 60 

Craft,  unrigged,  98 

Crew  required,  for  Diesel  en- 
gine, 131 

Crew  space,  deductions  for,   196 

—  discussion    of    deductions    for 

224,   225 

—  legal   requirements   regarding 

196 
Curtis  turbine,  adoption  of,  112 

H3 

—  description  of,  112 
Cylinder,    oscillating  %in    marine 

engine,    104-106 

—  stationary,  104 
Cylindrical  boiler,   117 

Danube  Rule,  for  propelling- 
power  space,  218 

—  objections  to,  222 
Dead  rise,  definition  of,  44 
Dead  weight,  actual,   163 

-  comparison  of  gross  tonnage 

with,   153,   154 

—  definition  of,   138 

-  maximum.  163 

—  meaning  of,   162 

—  measurement   of,    163 

—  scale,   164 

—  uses  of,   141-144 

Deck,  awning-,  vessel,  95,  96 

—  erections,  value  of,  171 

—  one-,  vessel,  72 

—  rules  for  construction  of,  243 

244 

—  shelter-,  vessel,  75 

• —  spar-,  vessel,  95,  96 

—  three-,  vessel,  69,  70 

—  tonnage,    179 

—  trunk-,  vessel,  84-86 


—  turret-,  vessel,  82-84 

—  two-,  vessel,  71,  72 
Deducted      space,      measurement 

rules  for,  179 
Deductions,    discussion   of   crew, 

,    224,225 

— •  discussion  of  navigation,    225- 
228 

—  discussion  of  propelling  power, 

219-224 

—  for  crew  space,  196 
Deductions  and  inclusions,  199 

—  for  navigation  space,  198 

—  for  propelling  space,    193-195, 

219 

Defects,    of    American    tonnage 
rules,  191 

—  of  turbine,  overcoming  the,  114 
Development  of  classification  so- 
cieties, 231-233 

Developments,  principal,  in  cargo 

vessels,  101 
Diesel  engine,  application  of,  to 

marine  propulsion,  125 

—  crew  required  for,  131 

—  description  of,  126 

—  disadvantages  of,   132 

—  four-stroke     cycle,    operation 

of,  127 

—  fuel  for,  132 

—  operation  of,  127,  128 

—  two-stroke  cycle,  operation  of, 

127,  128 

Direct-acting  engine,  104 
Disadvantages,  of  Diesel  engine, 

132 

—  of  electric  turbine  system,  114 

—  of    gear-wheel     transmission, 

H5 

—  of       hydraulic       transformer 

gearing,  115 
• —  of  Isherwood  system,  42 

—  of  oil  fuel,  123,  124 

—  of  producer  gas  engine,  125 

—  of  quadruple  engine,  no 

-  of  towing  unrigged  craft,  100 
Displacement,  actual,  158 

—  and  buoyancy,  157,  158 

—  calculation  of,  159 

—  and  dead-weight  tonnage,  141, 

157-175 

—  explanation  of,  157 

—  forms  of,  158 


250 


INDEX 


Displacement,    formula   for,   159, 
160 

—  importance  of,  in  war  vessels, 

158 

—  light,  158 

—  loaded,  158 

—  nature  of,  137 

—  uses  of,  141-144 

—  volume  of,   157 

—  weight  of,  157 
Displacement  scale,  161 
Division,  of  length  for  measure- 
ment purposes,  180 

—  of  tonnage  length  and  depths 

181 
Divisions  in  the  measurement  o 

gross  tonnage,  179 
Double-acting  engine,  104 
Double  bottom  and  floor  plates 

38 
Draft,  description  of,  44 

Earnings  of  line  and  tramp  ser 

vices,  64 
Economy,    relative,    of    line   and 

tramp  services,  63 
Efficiency  of  the  steamer,  9 
Electric  system,  advantages  of,  in 

turbines,  114 

—  disadvantages  of,  in  turbines, 

114 
Elements  determining  freeboard 

168 

Elements  of  safety,  229 
Engine,  beam,  103 

—  classification  of  marine,  104 

—  Diesel,   125 

—  oil-burning,  120 

—  oil-burning  and  internal-corn 

bustion,   119-134 
• —  oscillating  geared,  107 

—  oscillating,  description  of,  106 

—  producer-gas,  124 

—  reciprocating,    104-109 

—  semi-Diesel,  125,  133 

—  side-lever,  105 

—  trunk,  1 08,  109 

—  turbine,  104 

—  types  of,  103-118 
Engine  room,  44,  216 
Equipment,    rules    for    construe 

tion  of,  244 
Essentials  of  good  cargo  boat,  69 


Exempted  space,  179 

—  above  tonnage  deck,   188,  189 

—  as  a  prevalent  cause  of  diffi- 

culty, 190,  191 

—  below  tonnage  deck,  187 
Express   steamers,   definition   of, 

56 

—  purpose  of,  56 

Factor  of  safety,  165 

Factors,  in  British  freeboard 
tables,  1 68 

Features,  structural,  of  steel  ves- 
sels, 32-46 

Ferro-concrete  vessels,  27-29,  51 

Fineness,  block  coefficient  of,  53 

—  coefficients  of,  table,  169 
Fire-resisting   qualities   of   metal 

vessel,  24 

Flare,   description  of,  44 
Floating  power,  definition  of,  165 
Floor  plates,  38 
Fore-and-aft  rigged  ship,  4 
Form,  as  a  factor  in  freeboard, 

170 

—  of  a  vessel,  .51 

Forms,  of  displacement,  158 

—  of  tonnage,  relations  between, 

J39 
Formula    for    displacement,    159, 

1 60 

Forward  tanks,  44 
Frames,  nature  of,  35 
— •  rules  for  construction  of,  242, 

243 

—  and  shell  plating,  35 

—  transverse,  34 
Framing,  kinds  of,  32 
Freeboard,  definition  of,  165 

—  explanation  of,  66 

—  Naval    architects'    rules    for, 

166 

—  old  rules  for,  166 

—  various  rules  for,  166 
Freeboard  marks,  67,  172 
Freight  tonnage,  138 

Fuel,  for  Diesel  engine,  132 

—  requirements    for    1921    esti- 

mated, 119 

Full-rigged  ship,  4 

Full-scantling  vessel,  construc- 
tion of,  69 


INDEX 


251 


Gas  engine,  internal-combustion, 
124 

kinds  of,  124 

Gear-wheel  transmission,  advan- 
tages of,  114,  115 

—  disadvantages  of,   115 
German      rule      for      propelling- 
power  space,  219 

German  tonnage  rules,  203-228 
Great  Britain,  tonnage  rules  of, 

203-228 
Gross  tonnage,  176-191 

—  definition  of,  176 

—  general  nature  of,   177 

—  of  unrigged  vessels  in  United 

States,  99 

—  principal     factors     affecting, 

190 

—  principles     governing     meas- 

urement   of,    189-191 

—  process        of        measurement 

under  United  States  Rules, 
179-191 

—  rules   for  ascertaining,   176 

—  United     States     and     foreign 

countries'  compared,  139 

—  uses  of,   144-152 

—  what  it  includes,  189 

—  what   it   represents,    190 

Half -breadth,  43 

Hatches,  description  of,  44 

Hatchways,    179 

High-speed    passenger    steamers, 

56,  57 

"Hog,"   tendency  to,  23 
Hold    capacities,    illustration    of, 

155 

Hydraulic  transformer  gearing, 
advantages  of,  115 

—  disadvantages  of,    115 

Immersion  curve,  explanation  of, 
162 

Improvements  in  steam  naviga- 
tion, 103 

Impulse  type,  turbine  engine,  in 

Impulse-and-reaction  type,  tur- 
bine engine,  in 

Inclusions  and  deductions  in 
tonnage  measurement,  179, 
190 

Indirect-acting  engine,  104 


Industrial  carriers,  nature  of,  57 

—  purposes     for     which     estab- 

lished, 58 

Internal-combustion  gas  engine, 
124 

Internal-combustion  oil  engine, 
125 

Internal-combustion  and  oil- 
burning  engines,  119-134 

advantages  of,  129-131 

International  tonnage,  benefits  of, 
„  226-228 

—  uniformity  in,  227 

Iron  vessel,  advantages  of,  20,  21 
Isherwood  system  of  framing,  32, 
39-42 

Keels,  construction  of,  33 

—  kinds  of,  33,  34 
Keelson,  bilge,  38 

—  center,  38 

—  side,  38 

—  and  stringers,  36 
Knees,  beam,  37 

Lawson,  Thomas  W.,  description 

of,  5,  12 

Legislation,   load  line,    167,    174 

Length,   between  perpendiculars, 

44 

—  division  of,   for  measurement 

purposes,  180 

—  over  all,  44 

—  ratio  of,  to  beam,   52 

—  rules  for  measuring,  208 

—  for   tonnage    purposes,   meas- 

urement of,   180 
Lifting  power,   measurement  of, 

67 

Light  displacement,   158 
Light  spaces,  193 
Line    method    of    operation,    60, 

61 
Line  service,  comparison  of,  with 

tramp  service,  59 

—  contracts  of,  60 

—  earnings   of,  64 

—  extent  of  tonnage  in,  65 

—  rates  in,  64 

—  standardization  of  vessels  in, 

59 

—  types  of  cargo  carried  in,  59 
Line  vessel,  nature  of,  56 


252 


INDEX 


• — with  superstructures,  78,  79 
Liners,  cargo,  57 
Liveliness,   measurement   of,   67 
Lloyd's   Register,   description   of, 

234-236 

Lloyd's  rules  and  tables,  240-242 
Lloyd's  tables  of  freeboard,  1882 

167 
Load  line,  explanation  of,  66 

—  relation    of,    to    construction, 

66 

—  variations  of,  171 
Load  line   legislation,    167 
Loaded  displacement,    158 
Longitudinal    system,   39 

Marine  boilers,  117,  118 
Marine  engines,  classification  of, 
104 

—  types   of,    103,    118 
Marks,  freeboard,  67,   102 
Materials  of  construction,   18-31 
Maximum  dead  weight,  163 
Mean   draft,   meaning  of,  44 
Measurement,   by   Moorsom   sys- 
tem, adoption  of,  204,  205 

—  of  cargo  tonnage,   152-156 

—  of  dead  weight,  163 

—  of  depths,  209 

—  of  gross  tonnage,  divisions  in, 

179 

—  of  length     for    tonnage     pur- 

poses, 1 80,  208 

—  of     propelling-power     space, 

192-196,  216-224 

-  of  safety,   229-245 

-  of  tonnage  under   Suez   rules, 

203-228 

—  of  transverse     sections,     181, 

182 

—  summary  of  process  of,  208 

—  tonnage  calculation  sheet,  200 
Measurement    cargo,    nature    of, 

153 
Measurements,    principal    vessel, 

44 

Merchant  Marine,  classification 
of,  according  to  construc- 
tion, 30,  31 

Method,  of  measurement,  of  be- 
tween-deck  spaces,  186, 
211 


— ••  —  of  superstructures  and 
closed-in  spaces,  186,  187 

—  of  operation      of      line      and 

tramp    services,    60-61 

—  of      reversing     direction      of 

screw  propeller,  127 
Molded   breadth,    description   of, 

44          » 

Molded  depth,  description  of,  44 
Moorsom  system,   date   of  adop- 
tion of,  227 

—  measurement  by,  179-202,  204, 

205 

—  measurement    of  depths,   181, 

209 

Naval  architects'  rules,  for  free- 
board, 166 

Navigating  space,  discussion  of 
deductions  for,  225-228 

—  deductions  for,  198,  214 
Net  tonnage,  138,  192-202 

—  principles  of,    198-200 

—  references  on,  200-202 
New  measurement  law,  203 

Objections,  to  Danube  system  of 
propelling  deductions,  222 

—  to  percentage  system  of  pro- 

pelling     deductions,      220, 

221 

Oil,  characteristics  of,  as  cargo, 
89,  90 

—  disadvantages  of,  as  fuel,  123, 

124 

—  importance  of,  as  fuel,   119 

—  engine,       internal-combustion, 

125 

Oil-burning  engines,  advantages 
of,  120-123 

—  comparison     of,     with     coal- 

burning,  123 

—  and    internal-combustion    en- 

gines,  119-134 

—  nature  of,  120 

Old  rules   for  freeboard,   166 
One-deck  vessel,  structure  of,  72 
Operation   of  Diesel  engine,   de- 
scribed,  126 

—  four-stroke  cycle,   127 

—  two7stroke  cycle,   127,   128 
Operation  of  line  and  tramp  ser- 
vices, 60.  6 1 


INDEX 


253 


Oscillating  cylinder  engine,  104- 

106 
Oscillating  engine,  advantage  of, 

106 
Oscillating  geared  engine,  107 

Panama  rules,  compared  with 
others,  203-228 

—  principles  of,  224 

—  tonnage,  206,  207 
Parson  turbine,  in,  112 
Percentage  method  of  propelling- 
power  deduction,  217,  218 

—  objections  to,  220 
Pillars  or  stanchions,  37 
Platesi  floor,  35 
Plating,  shell,  35 

Principal  factors  in  gross  ton- 
nage, 190 

Principal  volume,  calculation  of, 
184,  185 

Principles,  of  gross  tonnage,  189- 
191 

—  of  load  line  regulation,  168 

—  of  net  tonnage,  198-200 
Private   ownership   of    industrial 

carriers,  advantages  of,  58 
Process    of    measurement    under 
United  States  rules,  gross 
tonnage,    179-181 

—  net  tonnage,  192-202 
Process  of  registration,  233 
Producer-gas  engines,  124 

-  advantages  of,  125 

-  disadvantages  of,  125 

—  parts  of,  124 

-  types  of,  124 

Profile,  43 

Propelling-power  space,  applica- 
tion of  rules  to,  192-196, 
216-224 

—  deduction  for,  in  paddle-wheel 

steamers,  195 
in  screw  steamers,  195 

—  defects,  of  Danube  rule  relat- 

ing to,  222 
of    German    rule    relating 

to,  219 
of  percentage  rule  relating 

to,  220,  221 

—  discussion  of  deductions   for, 

219-224 


—  percentage  method  applied  to, 

217,  218 

Propulsion,  classification  of  ves- 
sels according  to  methods 

of,  3-17 
Purposes,  of  beams,  36 

—  of  cargo  liners,  57 

—  of  vessel   classification,    229- 

231 

—  of  vessel  construction,  48-50 

Quadruple  engine,  advantages  of, 
no 

—  disadvantages  of,  no 
Qualities,    weatherly,   description 

of,  66,  67 
Quarterdeck,  raised,  construction 

of,  72,  73 
with  extended  bridge,  74 

—  short    raised,    illustration    of, 

75 

Raised-quarterdeck  vessel,  con- 
struction of,  72,  73 

—  advantages  of,  74 

—  with  extended  bridge,  74 
Rates,    in    line    and    tramp    ser- 
vices, 64 

Ratings,  comparison  of  classi- 
fication society,  244 

Ratio,  of  beam  and  length  to 
draft,  52 

—  ol     displacement     and     dead 

weight,    139 

—  of  gross  to  net  tonnage,   139 

—  of  length    to   beam,    52 

—  of      registered    tonnage    and 

displacement,    139 

—  of  vessel      and      cargo      ton- 

nage, 146 

Reciprocating   engine,    104 

Reciprocating  and  turbine  en- 
gines, combination  of,  115 

Recommendations  of  Board  of 
Trade  regarding  free- 
board, 173 

References,  comparison  of  meas- 
urement rules,  228 

—  displacement  and  dead-weight 

tonnage,  174,  175 

—  gross  and  net  tonnage,  200- 

202 

—  materials  of  construction,  31 


254 


INDEX 


-  measurement  of  safety,  245 

—  methods  of  propulsion,  16,  17 

—  oil-burning  and  internal-com- 

bustion oil  engines,   134 

—  structural    features    of    steel 

vessels,  46-47 

—  types  of  marine  engines,   118 

—  types     of     merchant     vessels, 

IOI-I02 

Refrigeration,    requirements   for 
92,  93 

—  systems  of,  93,  94 
Refrigerator      vessel,      construc- 
tion of,  91-92 

Registered    tonnage    and    cargo- 
carrying    ability,     relation 
between,    140 
Registers,   important  vessel,  236, 

237 

Registration,  process  of,  233 
Regularity  of  the  steamer,  8 
Regulation,  principles  of  load 

line,   168 

Relations,  between  displacement 
and  dead  weight,  139-165 

—  between    forms    of    tonnage, 

139,    140 

—  between    load    line    and    con- 

struction, 66 

—  between     registered     tonnage 

and  cargo-carrying  abili- 
ty, 140 

Relative  economy  of  line  and 
tramp  services,  63 

Relative  strictness  of  different 
rules,  gross  tonnage,  190 

Requirements,  of  law  for  crew 
space,  196 

—  for    vessel    refrigeration,    92, 

93 

Reserve  buoyancy,   169 
Rule,     necessity     for     arbitrary 

propelling-power,   216,  217 
Rules,       British       measurement, 

203-228 

—  for     construction,     American 

Bureau  of   Shipping,  242- 

245 

beams,  243 

decks,  243,  244 

equipment,  244 

frames,  242,  243 

shell    plating,    243 


—  for   freeboard,    166 

—  tonnage,  comparison  of,  203- 

228 

—  German    measurement,    2ov- 

228 

—  Panama    measurement,     203- 

228 

—  present-day  tonnage,  203 

-  propelling-power,   217-219 

—  Suez    measurement,    203-228 
• —  United    States    measurement, 

176-202 

Safety,    elements   of,   229 

-  measurement  of,  229-245 
"Sag,"  tendency  to,  23 

Sail  tonnage,  United  States,   12 
Sailing  routes,  of  the  world,  8- 

10 
Sailing  vessel,  3-16 

—  advantages  of,    n 

—  bulk  cargoes  and  the,   13 

—  cost  of  construction  as  a  fac- 

tor,  13 

—  decline  in  importance  of,  6 

—  disadvantages  of,  8 

—  effect   of   bounties   on,    15 

—  increased  size  of,  13 

—  in  irregular  trades,  13 

—  scarcity  of  tonnage  as  a  fac- 

tor,   13 

—  size  of,  in  United  States,  12 

—  tonnage  of,  in  United  States, 

M 

—  types  of,  4 

—  uses  of,  11-15 
Scale,  dead- weight,  164 

—  displacement,   161 
Scantlings,  construction  of  vessel 

with  full,  69 
Schooner,  definition  of,   5 

—  increase   in   size   of,   5 

—  modern,  illustration  of,  5 

—  rig,  advantage  of,  5 

—  steam,  construction  of,  95 
Screw  propeller,  methods  of  re- 
versing,  127 

Self-trimming    vessel,    construc- 
tion of,  86 

Semi-Diesel  engines,  125 
Service,  speed  and  character  of, 
55 


INDEX 


255 


Shade-deck  vessel,  description  of, 

80 

Shapes,   description  of,   42,  43 
Sheer,  nature  of,  43 

—  purpose  of,  54 

Shell  plating,  rules  for  construc- 
tion of,  243 
Shelter-deck  vessel,   construction 

of,  75 

—  development  of,  75,  70 

—  illustration  of,  77 
Shipping  Board  tonnage,   15 
Short    raised-quarterdeck,    illus- 
tration of,  75 

Side  keelsons,  38 

Side  lever  engine,  description  of, 

105 

Side  stringer,  38 
Simpson's    rule,    explanation    of, 

182 

Single-acting  engine,  104 
Sloop,  definition  of,  5 
Societies,  classification  work  of, 

67,  231 
Spaces,   included,   exempted,   and 

deducted,  179 

—  exempt,    above    the    tonnage 

deck,  188,  189,  212-216 
above    tonnage    deck    be- 
cause of  purpose,  188,  189, 
213-216 

below    the    tonnage    deck, 

187-212 

—  in  cargo  vessels,  45 

—  light  and  air,  193-213 

—  principal  vessel,  44 
Spar-deck  vessel,  construction  of 

97,98 
Speed,  and  character  of  service, 

55 

—  of  the  steamer,  9 

—  and    tonnage    of    high-speed 

steamers,  57 

Square-rigged  vessel,  3,  4 
Stanchions  or  pillars,  37 
Standardization  in  line  and  tramp 

services,  59 

Stationary    cylinder    engine,    104 
Steam  navigation,   improvements 

in,   103 
Steam    pressures,    utilization    of, 

104 


Steam  schooner,  construction  of, 

95 
Steamer,  advantages  of,  8-n 

—  whaleback,  construction  of,  80, 

81 

—  express,  56 

—  passenger,  high-speed,  56,  57 

—  increased  importance  of,  6 

—  tonnage  of,  in  United  States, 

14 

Steel,  advantages  of,  25 
Strains,   vessel,   22 
Strength,  iron  vessel's  greater,  21 
Stress,  transverse,  24 
Stresses  of  vessel,  in  still  water, 

22 

—  in  waves,  23 

Strictness,    relative,    of   different 

gross  tonnage  rules,  190 
Stringer,  36,  38 
-  bilge,  38 

—  side,  38 

Structural  features,  classification 
of  vessels  by,  68 

—  of  steel  vessels,  32-46 

—  of   steel      vessels,   references, 

46,  47 

Suez  Canal  Company,  measure- 
ment of  tonnage,  205,  206, 
203-228 

Summary  of  vessel  measurement, 
208 

Superstructures,  170,  179 

—  application  of  rules  to,  212 

—  and  closed-in  spaces,   method 

of  measurement,  r86,  187 

—  vessel  with,  45 
System,  longitudinal,  39 

—  Moorsom,     adoption     of,     by 

various  countries,  227 

—  transverse,  40 

Systems  of  refrigeration,  93,  94 

Tables,  American  Bureau  of 
Shipping1  classification, 
242-244 

—  Lloyd's  classification,  240-242 
Tank  vessel,  construction  of,  89 

—  purpose  of,  88 

—  illustration  of,  91,  92 
Tanks,  forward  and  peak,  44 
Three-deck    vessel,    construction 

of,  69,  70 


INDEX 


Tonnage,  British  rules  for  meas- 
urement of,  203,  204 
Tonnage  certificate,  copy  of,  1^9 
Tonnagedeck,  179 
— •  rules  regarding,  208 
Tonnage  displacement,  157-162 

—  definition  of,  137 

—  uses  of,  141-144 

Tonnage,  classified,  as  to  method 
of  measurement,  137 

as  to  object  to  be  meas- 
ured, 137 

—  comparison    of    measurement 

rules,  203-228 

—  dead- weight,  162-175 
definition  of,  138 

—  uses  of,  141-144 

—  distribution     of,     in     United 

States,  14 

-  employed   in   line   and   tramp 

services,  65 

—  engine  room,  216 

—  freight,  definition  of,  138 

—  German    rules    for    measure- 

ment of,  204 

—  gross,  176-191 

-  definition  of,  138 

and  net,   in   United  States 

and  foreign  countries,   139 

—  international,   226,   227 

—  items,    calculation    of    United 

States    and    foreign    com- 
pared, 197 

—  kinds  of  and  uses,  137-156 

—  length,   division   of,   181,  208, 

209 

—  net,  138,  192-202 

—  Panama  Canal  rules  for  meas- 

urement of,  206,  207 

—  present-day    rules    for    meas- 

urement of,  203-207 

—  sail     and    steam,    of    United 

States,   12,  14 

—  Shipping  Board,   15 

—  speed  of  high-speed  steamers, 

57 

—  'tween-deck,  defined,  179 

-  under-deck,  defined,  179 

-  under  the  tonnage  deck,  209 

—  United  States  rules  for  meas- 

urement of,  204-205 

—  various  meanings  of,  137 

—  volume,   forms  of,    138 


-  wood  and  metal,  30,  31 

—  world's   steam  and   sail,  6 
Towing,  advantages  of,   100 
Tramp  vessel,  55,  56 

—  typical  size  of,  56 
Transmission,       advantages       of 

gear  wheel,  114,  115 
Transverse  and  longitudinal  con- 
struction,   advantages    of, 
40,  41 
Transverse   frames,   construction 

of,  34 
Transverse  sections,  area  of,  181 

—  diagram  of,   183 

—  measurements  of,  182 
Transverse  stress,  24 
Transverse    system   of   construc- 
tion, 40 

Trim,  meaning  of,  44 

Trimming,  construction  of  self- 
trimming  vessel,  86 

Trunk  engine,  description  of, 
108,  109 

Trunk-deck  vessel,  construction 
of,  84,  85 

-  purpose  of,  86 

Tumble  home,  description  of,  44 
Turbine,    Curtis,    112 
Turbine,  Parsons,  in,  112 
Turbine  engine,  104,  110-116 

—  types  of,  no 

—  impulse  type,  in 

—  impulse-and-reaction  type,  in 
Turret-deck    vessel,    construction 

of,  82 

—  advantages  of,  83,  84 
'Tween-deck  tonnage,;i79,  185,  211 
Two-deck  vessel,  construction  of, 

71,  72 

Types,  of  cargo,  line  and  tramp 
services,  59 

—  marine  engines,  103-118 

—  merchant  vessels,  48-102 

—  producer-gas  engines,  124 

-  sailing  vessels,  4 

—  turbine  engines,  no 

—  vessels     employed,     line     and 

tramp  services,  61,  62 

—  vessels,  comparison  of,  116 

Under-deck  tonnage,   179 
Uniformity,  in  measurement  ton- 
nage, 227 


INDEX 


257 


United    States    legislation,    load 

line    1891,    174 
United  States  tonnage  rules,  179- 

200,  204,  205 
United  States  tonnage,  steam  and 

sail,  7 
Unrigged  craft,  98 

—  advantages  of  towing,  100 

—  disadvantages  of  towing,   100 

—  geographical    distribution    of, 

99 

—  number,    gross    tonnage    and 

value  in  United  States,  99 
Use  of  exhaust  steam,  104 
Uses,    for   vessel   tonnages,    140 

—  of  dead-weight  tonnage,  141- 

144 

—  of  displacement  tonnage,  141- 

144 

—  of  gross  and  net  tonnage,  144- 

I52 
• —  present  of  wooden  ships,  29 

—  of  sailing  vessel,  11-15 
Utilization    of    steam    pressures, 

104 

Value,    of    deck    erections    from 
freeboard    standpoint,    171 

—  of  reserve  buoyancy,  54 
Variance  of  load  line,  171 
Vessel,     awning-deck,     construc- 
tion of,  95,  96 

—  cantilever,     construction     of, 

87,  88 

—  combination,  57 

—  composite,  26,  51 

—  concrete,  27-29 

—  ferro-concrete,  27 

—  form  of,  51 

—  full-scantling      with       super- 

structures, 78,  79 

—  line,  56 

-  merchant,  types  of,  48-102 

—  sailing,  types  of,  3 

—  shade,  deck,  description  of,  80 

—  shelter-deck,     illustration     of, 

77 


—  spar-deck,      construction      of, 

97-98 

—  stresses,  in  still  water,  22 

-  waves,   23 
-  tonnage,  uses  for,  140 

—  tramp,  55 

• —  trunk-deck,    construction    of, 

84-85 

—  well-deck,  76 

—  with    superstructures,   45 
Vessels,  built  and  officially  num- 

i  bered  in  United  States  since 

July,   1916,  30 
Volume  of  displacement,   157 

Water-ballast   capacities,    155 
Water-tube   boiler,    117 

—  advantages   of,   118 
Wave-riding     qualities,     descrip- 
tion of,  67 

Weatherly    qualities,    description 

of,  66,  67 
Weight,    wooden    vessel's    extra, 

21 

Weight  cargo,  description  of,  153 
W'eight  of  displacement,  157 
Weight  tonnage,   forms  of,   137, 

138 
Well-deck  vessel,  76 

—  advantages  of,  78 

—  classes  of,  76 

Whaleback  steamer,  construction 
of,  80,  81 

—  purpose  of,  81 

Wood,    disadvantages    of,    as    a 
shipbuilding    material,    20 

—  difficulty   of   obtaining.   20 
Wooden   vessel,   construction   of, 

18-20 

—  extra   weight  of, 

—  limited  size  of,  21 
-  parts  of,  1 8 

World's     tonnage,     steam     and 
sail,  6 

Yarrow,    boiler,    description    of, 
"7 


CD 


14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

LOAN  DEPT. 

This  book  is  due  on  the  last  date  stamped  below,  or 

on  the  date  to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


;   .  -     v'iPM 


Rec- 


LD  21A-50rn-4.'59 
(A1724slO)476B 


General  Library 

University  of  California 

Berkeley 


YC  66357 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


t 


